DON'T.
Adminmod has NOT released a compatible version yet. So it effectively nukes the 1.1 moves.
Install AMX mod instead.
How to do it anywayz: (foo)
Unzip adminmod. Go to the unzipped directory. Finda script called install adminmod (or something similair) and run it.
This installs metamod + adminmod.
If you want to try AMX mod you got to seperately download metamod cause AMX does not suply it. AMX is a thingy of unzip the files and then move em in the addons map.