Advice please!

In 2002 my son's father sent him a Tag Heuer Professional Sports watch. I would like to sell it now because my son just will not wear a watch of any kind. Having said that I'm not sure how to go about it, I don't even know what the watch is worth. This is where I need the advice. It has never been out of the box in all this time so is brand new. People talk about whether the watch has 'papers', does this mean the instruction booklet inside the box? The number on the back of the watch face and in this booklet is WA1211. Can someone help please? I really need to sell this watch but don't want to let it go for peanuts. Any advice appreciated