Please go to the Listings Manager at the ECA Center and then click on the Edit Listing button. Below the item description, you will find where to add choice menus.
Click on "Create A Choice Menu". Create a name for your Menu Choice and an Menu Nickname for your information.
Under Menu Choice list one size per line. Put S or Small for the small size, then hit the + sign.
Then put in M or Medium for the medium size, then hit the + sign.
Then put in a L or Large for the large size, then hit the + sign.
Once all your sizes have been entered, then you hit the SAVE CHOICE MENU button on the right.
Then after you finished creating your choice menu, go back to your listings manager, select the listing you want to add the choice menu to, and below the description choice which choice menu you want to have on your listing.