To set up integration with eBay, go to Settings > Plug-in Settings > eBay tab.
You must sign up for an eBay Developer account before you can set up the integration. Once you have filled in all of the information under Plug-In settings, you can start adding products.
To do this, go to Inventory > View Products. On the righthand side under the "Action" column, hover your cursor over the tool icon. In the drop-down, eBay will appear down at the bottom. Click this and a new page will come up where you can enter in more information for your eBay product listing.