I ordered popper shaped lure from jannsnetcraft and i see there is no cup in the lip. How do i go about getting the cup to make the popping sound?

Is the bait wooden? Remove the line tie first and if you're very careful, you can use a small curved chisel to remove some of the material to give a concaved face, or a dremel would work nice too. Just be careful with both tools because they remove flesh as easily as wood.

ya, it is wooden, and i don't have the line tie in it yet. I have a sander piece that is  cylindrical, would that work?

A big over sized drill bite would work.   Problem with the popper is the clear coat tends to fill up the cup face.