Question about cutting a round bottom slot

[WillAdams (William Adams (Carbide 3D))]

see:

Creating 3d Path that is half round

I have read through Will Adams Github document but still dont understand how to model in Carbide Create 3d. The attached file is a project that holds a whiskey glass and a metal tray to be used as an ashtray. The center I want a half round place to place an un-smoked cigar. After I learn how to make the 3d image I want I will also make the same shape perpendicular that goes across the ash tray to become a resting area for a lit cigar. Can someone please point me to a tutorial about how to ma…