Tie some leader material (mono, hybrid or fluorocarbon) to your mainline (good mainline to start with is 6lb fireline- braid) using a double uni knot or an albright. 2 Rod lengths or so of leader should be plenty. Don't use a swivel.
A good quality 8lb leader is a good way to cover both flatties and bream. If you think your onto a good flathead - don't put too much pressure on the line as 8lb will not last too long in a flathead's mouth before being worn down.
I've caught lots of good size flathead and bream using 8lb YoZuri hybrid leader.
Its well worth trying to get your hands on the berkley soft plastics dvd, it gives a good rundown on getting rigged up and some simple SP techniques.
Don't go too heavy with the leader if your starting out as your likely to get more inquiries from fish when using lighter leader.
oddbudman