I don't know Chinese yet, but your English sounds perfectly fine for song lyrics. Keep in mind that except for text messaging and song lyrics, the word "wanna" is always spelled "want to." Actually, English spelling is generally more etymological than phonetic.

I don't totally agree with Phil or Robin, even though it's proper English to say "want to", it's not terribly different from the 'lazy' Cantonese. 我 is properly "ngo5", but lazy is "o", nei5 is lei5, and "gong2 ni1 di1" said, "gong li di"...it all depends on what you wanna do! :) Especially if the song is from a person like Prince.

The word "wanna" is a slang term used....you find it in songs, such as yours but I do agree with Phil that the correct English words to the phrase would be "want to". The word wanna is not an actual English proper word. Some Americans have gotten lazy to using the English language properly but on the other hand, song writers find it easier to use these slang terms to fit the rhyme of a lyric. Also, as Phil has stated, it is also used in texting short cuts for abbreviation purposes....and our younger generation. here at least, know more slang short cuts then the proper English words and the spelling of such. Lastly, you are way ahead on your English then that of true Americans. Keep up your hard work. It will pay off to you.