I cant find it! The game is available but i  dont remember where is the button

There is none. Just post to the game ad and it will bump. It can only be done once per week. the screen even has a timer counting down to when it can be done again.
This message was last edited by the user at 18:03, Tue 16 Sept 2014.

In reply to Merevel (msg # 2):

thankyou... I've found a bump stuff inside game thread and I get confused

I'm not really sure that ever happens if you're just a player, but I do have a bump button when I'm GMing a game.