Alright, first off the first thing you want to do is to draw a circle preferrebly 5-7 inches in diameter. Then your gonna want to click on extrude boss/base.
Step 1: Simple Cupholder
Then once you have clicked extrude boss/base, you come up with this solid feature. And the reason my cylinder is blue is because i went to appearances and clicked the color i wanted on the body that choose. Now what your gonna want to do is draw another circle on top of this cylinder as seen on my picture,once you've done this you need to extrude the newly added circle. and make the extrude cut go a little less than halfway down becuase your gonna have to do something else explained in the next step.