First, you need to understand one important thing: 'wanna' is NEVER an alternative to 'want'. It represents the two words 'want to'. When native speakers are speaking fast, informally, or in a relaxed way, the two words 'want to' run together, so that it sounds like we are saying 'wanna'. For example if we say 'I want to go home' this can sound like 'I wanna go home'. But remember that this is simply a way of representing a sound. It is not a standard feature of English grammar, and it is not an accepted abbreviation (like "I'm" or "don't", for example). If you want to know more, take a look at this discussion: http://www.italki.com/discussion/85918 Gonna wanna

Reduced forms like "wanna" have no place in written English unless a person is using dialog, reported speech. I know reduced forms are common in ordinary conversation, but avoid using them in writing.

[I'm a non-native speaker] Saying "I wanna" is maybe a bit of an Americanism. Means: "I want to" These words are frequently used in speech in informal English, particularly American English. I want to buy a car. I wanna buy a car. Both are the same, but the second one is informal. I think that British people don't use those words so much. For example: (US) I gotta go (UK) I've got to go In my opinion, it's better to NOT to use these words. Even if you're learning the American version of English. Hope this helps ;)

Wanna - forma coloquial de ( I want to ) I wanna eat breakfast now / I want to eat breakfast