If you mean admin of your server running ULX, we can help you.
Start by reading the readme files included with ULib and ULX. They're in your addons/ulib and /ulx folders.
One of them points to a Gmod wiki article that tells how to add yourself to GMOD (not just ULX) as a superadmin.
Follow its instructions to the letter.
See our FAQ section also.
/index.php/board,30.0.htmlIf you're asking how to host / run the server in general.
See the Gmod wiki for how to host a server, lots of good general info.
http://wiki.garrysmod.com/?title=General_Server_Setup_InformationSee the Gmod wiki for how to administer.
http://wiki.garrysmod.com/?title=AdminIf you're needing more information about your actual host provider, go see thier support documentation/forums.