user->getPermission

If you want to check wether the user is a supermoderator you could use

WCF::getUser()->getPermission('mod.board.isSuperMod')

The return value may be used for boolean checks (since 1 is regarded as true). Some Permissions can return arrays or even strings, it heavily depends on the stored data. In general most values are boolean.

The technical documentation does not mention this topic so you should check out the api documentation available at http://www.selbstzweck.net/wcfapidoc/ . If you select "com-woltlab-wcf-data-user" you could find the method "getPermission" there.

In fact it's up to you wether you use that api docs (frames are lame!) or read yourself trough the sourcecode and figure out what the classes and methods do on your own.

You could try reading trough the official Technical Documentation as it explains a huge amount of features. If you're still unable to solve your problems you're always welcome to ask your questions