I believe you got to know each other well and you are confident making such decision. I assume he wanted to come to the US. He may apply for a tourist Visa with your letter of invitation, just a simple signed letter with your contact info and a letter from your employer as a proof of employment or a business papers showing that you have sufficient iui client income to support a guest. There is a high chance he will get the visa if he his employed or has a business that is convincing that he will go back and stay in the US. On the other hand, if you want to visit him in Algeria, the go to Algerian Embassy website and it shows the documents needed to get a visa. You need to fill the application, send a money order for $160, send two passport pictures, send a copy of around trip ticket to Algeria (make a reservation with an airline for a future date to get a confirmation, save the confirmation of the itinerary, and cancel the reservation), send a letter of invitation from you fiance'.
You can apply for a tourist visa to go visit him, or invite him as your fiancé and once he is in the US, marry him.
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