The My Sub-Stores tab within a Studio gives you the Studio owner the ability to have an easy access point to all of your sub-stores.
You will need to open a sub-store in order to post content for sale. Studios may open as many sub-stores as they would like.
To add a sub-store you will need to enter your "My Sub-stores" section of your account.
Once here you can select the "+ Add Sub Store" button in the right hand corner.
You will then be prompted to enter your preferred username for your new sub-store.
You can login to any of your sub-stores from the "My Sub-stores" tab inside of your account. You will need to login to whichever sub-store you wish to access.
Once logged into your sub-store you can easily return to your studio view by clicking the pink "Return to Studio" button at the top of the page.