I just bought the Wolfgang Puck Bistro Collection Pressure Cooker through eBay, but it didn't come with instructions & I don't quite understand how the blue pressure knob and the red knob (on top of the blue) are supposed to work....they flip from 4:00 position to 7:00 position, but I'm unsure of which should be where when I use the presure cooker. Help!?

Refrigerators - Presto - 6-Qt Stainless Steel Pressure Cooker with Bi-Clad Bottom