Firstly, STOP your server if you edit your users.cfg or the configs will NOT change.
Log into your ClanForge and select the server you wish to assign yourself as admin.
Select the "Stop" button, shutting down the server will allow any changes to the configs to remain once started back up.
In here you will want to place in either;
ownerid "Steam64ID" "SteamName" "Reason"
moderatorid "Steam64ID" "SteamName" "Reason"
ownerid 5983275893749327 "Multiplay" "Server owner"
moderatorid 5983275893749327 "Multiplay" "Server moderator"
After you have entered all your details you will need "Save&Apply" this will apply all your settings and will bring your server back online.
Once you have done that you will want to type in server.writecfg
This will save everything you have placed on console into your configurations.