An immigration lawyer is always an asset, although they can be extremely expensive, but not a necessity. I had hired an immigration lawyer to assist with my husbands case, and after spending almost $5000, they had done more harm than good, and i ended up taking over.
Bad news is, depending on how and why he was deported, he may not be eligible for immigration. People who have been deported because they were charged/ convicted of a crime have very little chance of returning. The US. has some of the harshest penalties in that sense.
The actual process of filing for immigration really is simple, but there are many formalities which complicate things
If you can clarify please; how and why he was deported; How long was he in the U.S. before he was deported? Are you an American Citizen? Is his name on your childs birth certificate? where have you been living since he was deported? how often have you seen him? and where/when did you meet etc. I think i may be able to help you further.

We met 5 years ago. At the time of deportation he hhad been here for 13 years. My daughter has his last name but he was not present at the birth because he was threated by an old girlfriend that she would call immigration on him, and ultimately she did. he was deported because he was illegal. No crime committed. I'm an american citizen. When he lived here we seen each other every weekend. I still intermingle with his family that is here

Down in Brazil, you would consult with an immigration agent who works closely with an immigration attorney there.

They will guide you through the whole process.

You should contact them prior to your marriage to make sure that everything is done properly, in the best possible order of events.

Prior to marrying, your fiance would get a visitor's visa to the US. But after marrying, you are restricted, per rules, to applying directly for a permanent residence permit (green card) for him while he is still in Brazil.

You'll have to marry him there, then go back and forth visiting him for about 9 months while the application for the permanent residence (green card) is pending (going through all the red tape).

You'll have to fill out forms, and when he finally goes for his interview at the US consulate in Brasilia, you will be advised that it's best for you to go with him.

Best of luck to you. I'm married to a Brazilian too.

If he is not listed on your daughters birth certificate he will have to be added. You just need to contact vital statistics for your state, and they should be able to assist you with that.

Next step would be for him to file form 'I-212 application for permission to reapply for admission into the United States after deportation or removal (go to USCIS(dot)gov and on the top right corner is a search box just type in I-212 its the first result). Now for the bad news: depending on his deportation papers, he may not be able to apply for readmission until 5 years after the date of deportation (this is the standard minimum).

If this is the case, and you do want to continue to be with him. All i can suggest is visit him as often as you can. Make sure you keep copies of your airplane tickets, itinerary, receipts for shows, movies, whatever you guys do. As well all phone bills proving you call each other, letters, emails, anything that will help prove you are maintaining your relationship out of love and not for a green card.

There are a lot of rules, exceptions and circumstances that come into play regarding illegal presence (and resulting penalties) of an alien overstay. Without knowing the exact details and methods of this persons entry, departure, re-entry, etc. The most anyone here can do is provided educated guesses as to what does and does not apply to your fiance.

That being said, I'm assuming the following:

If he was in the US for 13 years, I would assume he accrued more than 1 year of illegal presence and probably worked without authorization.

You admit he was deported.

You claim he has no criminal background/record (aside from the obvious overstay and assumed work without authorization).

Based on that (little) information (and providing immigration law doesn't change), he will be subject to the following:

Overstay+Deportation = Inadmissible alien.
Departure from the US after more than one year of illegal presence = 10 Year Disbarment.

Before he can even apply for entry into the United States he must file an I-212 Application for Permission to Reapply. The period in which you must obtain consent to reapply is 5 years if he were removed once, 20 years if he were removed twice or more and forever if he was convicted of an aggravated felony.

Once he obtains permission to reapply, you will file a K-1 Fiance Visa if you are not yet married, or a K-3 Spousal Visa if you are married. Note, regardless of which one you file - because of his inadmissibility, this will automatically be denied.

Relief may be obtained in the form of the I-601 Waiver of Inadmissibility which can be filed immediately when the K-1/K-3 Visa is denied. The I-601 requires proof of hardship to the US Citizen and carries a high standard to acquire. Note that the typical hardships of being separated carry little (if any) weight in filing an I-601.

Should you fail to successfully obtain an I-601 ruling in your favor, you (may) be able to appeal and provide additional evidence to support your claim. Should your appeal fail, I know of no other way to obtain relief. You'll have to wait until the 10 year disbarment has been satisfied before trying again.

Once the disbarment has expired (or immigration law changes) you may start the process over with a (relatively) good chance of success (providing no further criminal record and no further attempts to re-enter on his part).

Given the complexity of your situation, an attorney would most likely be a valuable asset.

If he was deported, you can still marry him and file a petition for him; however when deported he is given a certain amount of years where he is not admissible to the USA. Some people get 10 or 20 years. You still can file the application, and it is a big chance that it will be denied. After it gets denied you must file for a waiver. You will then explain (Or your lawyer) why is your husband necessary for you in the USA (Hardship, ilneess, etc). The best thing is to hire a lawyer that is experienced in deportation cases. My fiance is Brazilian too, and I have to travel back and forth after living together for 15 years, because he is not admissible in the USA at this time :( I hope your case has a better outcome.. Good luck!