How to Change a User's Permissions Role

As moderator, administrator, or site creator you have the ability to promote (or demote!) other users.You can do this by going to that person's profile page and clicking on "Change Permissions." There, you can assign them a new role.
It wil give you the options to Change the users role higher or lower.Pick the role you want them to have and your Done!

Promoting Moderators

Promoting users to moderator status will give them access to more editing capabilities and it will give you some helping hands on the site. Although you should never count on others to do your job for you, there is nothing wrong with volunteer help from your promoted users. In fact, it will help to build a solid online community and give people a reason to participate in the site on a regular basis.

See also:

• Moderating Guide