I guess I will help seeing as no-one has responded yet..
I don't think I want to type it all out in one sitting so I will walk you through it as you complete the previous step.
I guess the first thing you need to make sure you have is the source dedicated server, or the valve dedicated server. You can find these by going to your steam "tools" tab and downloading the appropriate one.
Sadly, Mani cannot be used on anything other then TF2 and CS:S. However, there is another option called AMX mod X which is essentially mani for 1.6 and lower.
You can find all needed information
here.
Post again when you are done those steps.