Hi there, I'm fairly new to Solidworks and I'm slowly learning. I've been scratching my head all afternoon because I can not figure this out. Basically I want to make a small groove for an O-Ring to fit around a hole. I have uploaded my model (I've stripped everything down except for the hole and the two sketches that show the groove size). I know that there is a toolbox feature for Grooves but I can't seem to figure it out. I've uploaded a picture of the  part highlighted with regards to what I want to do.

The O-Ring has an outer diameter of 0.4375" and an inner diameter of 0.3125". The depth of the groove should be 0.0320".

To get an idea of what I want to do, here is a good picture at the very bottom of the page that shows an O-ring placed(on a much bigger scale of course!):

http://mtnhiperf.com/fire_ring_pictures.html

Any help would be appreciated.

Thanks.