Mikendher: check out our info page
http://www.livejournal.com/userinfo.bml?user=cdoftheweekfor detailed instructions.
And check the memories section for actual examples of mixes.
Basically, you see the theme announcement each week and go to work selecting songs to make into a mix cd that fits the rules listed on the announcement.
Most of them are open ended, but there was one mix where every song had to be under 3 minutes (i.e. the perfect pop song), so you could only pick songs under that length of time. The basic idea of making a mix is to limit your song selections by some sort of criteria so that the final product expresses some sort of mood, feeling, or purpose. The final result should be cohesive and should be readily identifiable as a "driving mix", "love mix", etc.
If you need help or any more info, feel free to send me or musikdork228 an IM.
Thanks to KharBevNor for joining and posting an awesome mix!
Hope to see more of you join in.