Use the below link. It is well explained(step by step). Also it is noob-friendly . I see u joined last month.
Since you are already on JellyBean you need to follow from section B. Skip section A. GOOD LUCK.
Press THANKS ONLY if I was helpfull
Please anybody suggest how to make my Samsung Galaxy S Advance I9070 jellybean DDULP8 Indian version fast and battery efficient. I read that making stock samsung jellybean to google stock jellybean (like nexus) makes device faster. if not possible suggest any rom or kernel to flash. please suggest with brief method i am new at it and i dont want to downgrade to gingerbread