and i have no idea how to look after it!

after bringing it home and reading the tag, it says it needs regular pruning to keep it's shape up... how do you do THAT? Just chop off any random bits? When do you do it?

I'm determined not to kill this thing as I'm wanting to plant 5 standard roses out the front of our house, and at $66 a pop, Mr Bonsai is my little plant guinea pig to prove myself worthy!

Any tips would be appreciated! xx