wanna=want to?

wanna 是美式口語, 等如 want to,
所以 說 I wanna say 就可以了. 基本上美式口語不太著重 grammar, 也經常把正統的英語作縮寫. 如 gonna = going to; gotta = have got to; dunno = I dont know; aint = are not, oughta = ought to..等等, 但印象中, 黑人比較喜歡說這種省卻的文法.

以下是有關英式和美式的英文差異.
http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv165.shtml

http://www-personal.umich.edu/~jlawler/aue/gonna.html

http://www.geocities.com/Athens/Atlantis/2284/

http://www.woodlands-junior.kent.sch.uk/customs/questions/americanbritish.html

wanna = want to.
wanna 係口語講法.

就好似 see ya = see you 咁樣.

所以你可以用「I want to say」, 「I wanna say」, 但係「I wanna to say」文法上係唔正確既.