After you steal the computer, the only real way to remove the lock with out damaging the computer is take the frame apart and use a dremmel tool to cut off the locking hook.
Oh, you mean how do I use it.
Get a lock that fits snugly against the lock slot. It wont prevent all kinds of theft, but it's a good security measure.
I'd suggest a combo kind. Kingston is reputable. If I were at a coffee house, I'd still take my computer with me if I were to get up for a time.