Webstore does not create a store on eBay, but a storefront outside of eBay for your eBay items. This helps you promote your storefront and drive more buyers to your listings from social networks and search engines.
Check out our comparison between an eBay store and Webstore storefront: http://support.3dsellers.com/qa/150/ebay-storefront-or-ebay-store?show=150#q150
You can also read here how you can advertise your storefront in your ebay listings: http://support.3dsellers.com/qa/152/how-do-i-link-my-ebay-account-with-my-webstore?show=152#q152
If you have any other questions feel free to leave a comment here below.