5
Very simple :
1 - Upload and overwrite all the files from the upgrade pack to you site.
2 - make a backup of the mainfile.php
3 - CHMOD 777 to the mainfile.php
4 - run the upgrade file (
http://www.you site/upgrade/html\upgrade\xoops_206_to_207.php )
5 - if the upgrade say that all is correct , CHMOD again to 644 or 444 the mainfile.php
6 - Delete the upgrade folder.
7 - login , go to admin > system admin > modules > and upgrade the system admin module.
8 - Enjoy.