Not so hard.
Find your store on the eBid stores page (eBid front page top right eBid stores)
Look at the catagories and look for the section your store is in
Find your store in that catagory and click on it
in the browser (top of the page) is the link to your store ( it will start
https://www.ebid.net/uk/stores - - - - )
this is you store web address, copy it
in your listing, use the Advanced Editor option to add the information to your listing, type in details as normal.
Once you have added your details text, find a place on the page to add your link and click on that ( it's a good idea to to tell people this is a link to your store) then at the top of the advance listing page go to the link symbol (see picture below) and paste in the copied link to the text box and apply. You can change the size and colour of the link text once the link is in the document.
That is your link added. Use this page as a template for future listings or bring up the page as a normal buyer would and copy the link and associated text and add that to other listings in edit mode. The copied text will be formatted in the same way as the page it is copied from.
Once you get the hang of this, you can experement and add the link to just a word ie press HERE to see my store.
Never tried this on bulk edit but I am sure it can be done by the copy method as it is, after all, only text
Hope that helps