Hi Ximena, "wanna" is the informal, slang way to say "want to", so you'd use it in casual situations whenever you mean "want to". So, "Do you want to go to the party?" becomes "Do you wanna go to the party?" I'd only use it when you're speaking to friends, not in more formal situations like work or in writing, but it is useful because it sounds natural and casual because many (if not most) Americans say it instead of "want to" without even realizing it.
Use "want" instead of "wanna" when you are saying "want" without "to" directly after it. As in, "I want ice cream." or "I don't want coffee."
Hi! I think both can be used in all sentences but "wanna" is an informal way.. when you use wanna you have to cancel "to" for example:
1- I want to study English.. (formal way)
2- I wanna study English..(informal way)