http://www.ibisgaming.com/forums/showthread.php?t=3043

I added a detailed part for demos. Additionally, you'll also find a useful command list for new admins.

TL;DR version is

"record <file name here>"
"stop"

You can play your demos in CStrike if you type into console:

"playdemo <file name here>"

Press shift-F2 to bring up the player while viewing the demo to control speed and the like.