Just as you select "sell," you will be transferred to a page that will help give you some insight on how to sell. There will is a text box in which you will be asked to lightly state what you are trying to sell.

Furthermore, other than the diagram given below, there is even a video provided by eBay , which I highly recommend watching first before proceeding any further.

Reading this before moving on will help you get a basic idea for what is asked to sell on eBay.