slang American ?is it necessary to us ?

slang American ?is it  necessary to us ?what's the right way we should follow it to get it correctly .

When we listen to music or watch movies . We found and notice a lot of difference in pronunciation aganist which we studied it  .

 like

i get to go right now  but in slang American it's like this (writing)  i gatta go right now  (pronunce) i garra go right now .

there are a lot of things like that  .

 i wanna get correct way to learn that with american idioms and pronunciation  .

anyone have any idea or any information about that just write it below .

I think you have to listen too much and practice talking but do not be too restricted . Because I think we learn English in order to communicate with others . It all comes with time when you practice English but don't make it (the accent) a goal . It doesn't matter for me to talk the American or the British or both mixed . The important for me is to convey my ideas and believes .

for pronunciation, I think these two sites will help you :

http://www.wordreference.com

http://onelook.com 

good luck lone ^_