To record a demo, it is a very simple thing to do.
We DO have HLTV for our servers, so if you are unable to record a demo, find out how much time is left on the map, so we can get an estimate on when the offense occures within the HLTV demo. You can obtain the HLTV demo by going to the HLTV section on forums and finding the map name within the list. Do keep in mind, the most recent maps are on the bottom.
As for recording demos yourself, there is one sure fire way to do that. Go spectate and spectate the person you suspect of rulebreaking/hacking. Once the round starts or they are alive, go to console and type record macho. The demo will then start recording the demo under the name macho.dem. Preferebly it is good if you record the demo for a total of two rounds to have a good sample size of the player hacking or rule breaking. However, some hacks are incredibly blatent that it just takes a few seconds to see. The less blatent it is, the longer of a demo. But be sure not to record massive demos. Keep it within 2-3 rounds and if you need more evidence, record macho2.
Once you have your demo, you'll need to upload it. I personally use mediafire. So go to mediafire and upload the file located in your cstrike folder. Steam/steamapps/common/half-life/cstrike. You'll find the demo there located as macho.dem and macho2.dem. You then upload those to mediafire and share through the forums, which we will look at and review.