i don't remember or shall i say what i think is pickpocketing is not working for me pls someone help thanks
Well, when you get to the guys that you need to steal something from them, you have to first make sure your close enough, but not too close. Use the Left Trigger to target them (just like you would if you were interrogated or eavesdropping). They will have a conversation and when one of them leave, wait till the one you have targetted starts walking. Walk up behind him and hold down the B button. Altair should hold out his hand and grab the item.
You can also practice on thugs when you get throwing knives.
Just remember, if the guy stops walking, don't try to pick pocket him because he will turn around and see you. Make sure you do it while he's walking.