TOTAL NEWBIE PLEASE HELP

[eluser]sHoyRu777[/eluser]
yes, ive already read that.. ahm i just want to convert this native php code to a CI code -->> $_SESSION['product'][$_GET['product_id']]++ ... if you could just please help me convert it to CI code then im done.. coz the ++ sign wont work on CI... ive tried everthing that i can possible think of but ends up stock...