Sogtware to control computer usage

How about you password protect your admin account, and don't give the children admin rights on their accounts.

i live in hostel and my room mates use my account so i cant create new accounts for them. we all use the same account and most of the time they use my pc because i remain busy

i want that torrent should be running all the time.........
if i create new accounts does the torrent running?

You can create new user accounts, and only allow certain software to be seen by the other user accounts.