How Do You find a certain Forums ID
-Sexiest
Generally, forumdisplay.php?fid=1 , here 1 is forum id.
In case of MyBB Community Forums, for example, support forum,
http://community.mybb.com/forum-127-page-1.html , 127 is the forum id.
You can also login ACP and go to Forums & Posts tab and get the forum id.