Hey guys, I don't really understand how it done, and I hope you could answer me and make me a bit smarter
I hope this is the right place.

If I'd want to make a website in which every user could deposit any amount of bitcoins in his account balance(and withdraw), how it can be done?
(not the website itself, the deposit/withdrawing 'method')
I'll need a different bitcoin address for every user and I'll need to know how much they deposited every time.
I have seen a lot of websites that are doing it, but could not really understand how it is done, if you could refer me somewhere that can help me on this topic, I would appreciate it!
Any info that is related to that topic(dangers, things to pay attention to) would be appreciated as well.

Thanks !