There are several versions, mostly in the Editors Depot - Tutorials - References. The Unofficial command reference guide is a little old now but still excellent.
The only exception is the online version, which you can access directly from the Editors Depot homepage. Look down the left hand menu column till you find COMMAND. It is just the official comref but with added Comments, which can be very useful.
Whenever you see a command mentioned in the forum that you want to use, you should always [/i]check it in the comref. Although forum posts are almost always substantially correct, copying and pasting directly from a forum post rarely works. In any case, unless you get to understand how a command works you won't have learned anything.