Moment of Frustration

 From:  s7r83dg3
Hey, How do I boolean difference a shape that sits inside another shape? Take a solid block and boolean difference a circle out of one side. Use the new edge as a rail for sweep along curve and draw a curvy curve onto the block and sweep it so it sits inside the block. I'm lost ,,, I can't even select the shape...

I need something like sweep along curve and subtract at once i think ..