The word 'gonna' is incorrect grammatically. The equivalent in proper grammar would be 'going to.' When using the word 'gonna' you are telling someone what you are planning to do at that moment or in the near future.
Learn English speaking much FASTER by downloading the TalkEnglish Offline Package and submerge yourself with over 8,000 audio files and over 800 pages of lessons! Then you can study without Internet connection and also listen to audio files using your MP3 player at any time. Go to the English Download page and download today!