I have cakewalk 3 and i use a behringer xenyx 802 mixer with it. In the past only recorded one track at a time. Now would like to record drums with 3 mics. I have the imputs on the mixer, but how is this done with mixer and cakewalk simultaneously? Anyone know or have a diagram?

simply connect your MAIN OUTS to the soundcard INPUTS.  set up 2 audio tracks, one with the LEFT INPUT and the other WITH THE RIGHT INPUT

OR set up ONE STEREO track with the STEREO INPUT to your soundcard.

but you're going to get the MIXED stereo version that way, not 3 or more separate channels.  in order to record 3 or more channels you have to have a soundcard capable of more than 2 inputs and you have to upgrade to X1 Essentials, Studio or Producer.  MC is limited to 2 simultaneous inputs.

The Xenyx802 only has two mic inputs. Where are you seeing the third?

In MC you are limited to 2 tracks at a time max.... you should upgrade if you really need to record 3 or more tracks at the same time. 

You could use a mixer to record a band with as many channels as the mixer would allow...and send the stereo out to the 2 channels in on MC and your sound card..... but it would be kinda like the old days where a big tape is rolling and you get it in stereo..... punch in fixes would be possible but everything would have to be the same.... instrumentation, volume, tone, etc..... oh yeah...and tempo too.