you can do it yourself without specific tools, but if you don't know much about it you might wanna bring it in to your lbs an have them tighten the stuff.

you can tighten your cog via rotafix method.
and then you can tighten the lockring with a screwdriver and a hammer. put the end of the driver (preferably flathead) into the notch on the lockring, bang it with the hammer to tighten. remember: lockrings are reverse threaded--i.e. lefty-tighty, righty-loosey.