There are two red dials on your BB7's that move the pads in and out. You can adjust them to cure a slight disc rubbing.

If the caliper is not aligned well with the rotor you need to loosen the mounting bolts. Use the red dials to position the caliper and tighten the mounting bolts and then dial back the pads to get the clearance you like.

Here is the BB7 User Manual.

http://www.sram.com/sites/default/fi...15-008-000.pdf

If that sounds too complicated take it to your LBS. They sort it out in 5 minutes.