Visit YaBB! YaBB 2 Quick Installation Guide - Installation 2
In your 'cgi-bin', create a directory called "yabb2" (or whatever name you wish to use). If you do not have a cgi-bin, then first create a directory called 'cgi-bin' and then inside that create the 'yabb2' directory. The example structure is provided in the YaBB package you've downloaded.

You should have a folder structure similar to the following:

	cgi-bin/yabb2/
	cgi-bin/yabb2/Admin
	cgi-bin/yabb2/Boards
	cgi-bin/yabb2/Help/English/Admin
	cgi-bin/yabb2/Help/English/Gmod
	cgi-bin/yabb2/Help/English/Moderator
	cgi-bin/yabb2/Help/English/User
	cgi-bin/yabb2/Languages/English
	cgi-bin/yabb2/Members
	cgi-bin/yabb2/Messages
	cgi-bin/yabb2/Modules/Digest/Perl
	cgi-bin/yabb2/Modules/Upload/Cgi
	cgi-bin/yabb2/Sources
	cgi-bin/yabb2/Templates
	cgi-bin/yabb2/Variables
	
Then, in a section of your webspace (outside the cgi-bin, generally in a 'public_html' or 'htdocs' folder, as suggested in the package's folders), create another directory called 'yabbfiles'.

You should have a folder structure similar to the following:

	yabbfiles/
        yabbfiles/attachments
	yabbfiles/avatars
	yabbfiles/Buttons/English
	yabbfiles/ConverterHTML/images
	yabbfiles/Smilies
	yabbfiles/Templates/Admin/default
	yabbfiles/Templates/Forum/default