Your amplifiers should have RCA type connectors on them.
5 channels of amplification = 5 amplifiers.
Connect your 5.1 preamp outputs to 5 amplifiers, then connect the 5 amplifiers to 5 speakers. The .1 is for your subwoofer, which likely has it's own built in amp.
There are lots of good 5.1 preamps on the market that include A/V switching and other features you may want including 5.1 analog input, analog inputs, surround DSP modes and things like that.
A company like Rotel has a couple of nice models that will go nicely with good amps:
http://www.rotel.com/products/surround-sound-processors.htm
Good way to go to maximize versatility and performance.
So, hook up all your equipment to the preamp/processor, hook the pre-outs from the processor to the amps, hook the amps up to your speakers, plug everything in.
Press power 'on' button.