"Wanna" and "Gonna" are very informal and should generally only be used with friends and family in spoken conversation.
Wanna = Want to. ie. Wanna go to the store? = Want to go to the store?
Gonna = Going to. ie. Are you gonna go to the store? = Are you going to go to the store?
"Got" is the past tense of "Get." I got a banana at the store. What did you get at the store?
Additionally, "Gotta" is an a very informal way of saying "have to" meaning "need to". I gotta go to the store = I have to (need to) go to the store.