How to Bi-amp??

I realize this is a stupid question, but always wanted to know and have two amps, one doing nothing.

I have bi amp able speakers and a 305 wpc amp, and another 255 wpc amp.
I like to try running the 305 to the drivers and the 255 to the midrange and tweeters.
Is this very difficult to do? Could you tell me what cables I would need to do this?
I have enough speaker wire to run from the amps to the speakers, just not sure what I need from my preamp to the amps.

Sure appreciate it.

Thanks to all that reply.