How to make an extruded cut from a 3-D sketch?

Hi everyone,

I know this question has been asked before and I have gone through almost all the discussions on this topic but I can't get my head around this. I have created a 3-D sketch from a curve and I need to cut extrude this shape/sketch (formed by the gray lines) to a depth of 2mm. What's the best way to proceed provided I already have a 3-D sketch?

Thank you,

CJ

SolidworksSurfacing