I am going to be a Mother soon and I want my son or daughter to be bilingual, and be able to speak Spanish and English. My significant other is half Cuban, and understands Spanish. But he doesn't speak it. I have always loved the Spanish language and was wondering the best way to teach my child to be bilingual? Since neither of us speak spanish I know that is going to be hard. I do have spanish speaking friends, but I don't see how that will help with this situation.

Any opinions would be greatly appreciated.
Where do you live?

You might investigate bilingual schools or even extra-curricular Spanish classes apart from regular schooling. Maybe even a private tutor, although that could be spendy.

Apart from the schooling aspect make sure he is still involved in some sort of Spanish-speaking at home as well, weather it be television, such as cartoons, music, reading children's books in Spanish. Etc...
He already understands Spanish, thats a good step, everything he needs
now is being surrounded by all of those friends of yours, and ask your
friends to invite your son to participate into the conversation, may
be asking some interesting questions, any curious could make it work.
Give him a chance to be part of the conversation, where he is the
special character, topics holding interest for him.