The Store Locator Manager can be accessed from the Marketing Menu by clicking on Store Locations. The landing page is shown below.
You have two options for updating your stores: Mass Upload, and Manual Upload. By default the landing page displays the form for the Mass Upload in the upper left. You can switch to Manual Upload by clicking the link above the form.
On the right of the page is a location summary by country. You can change the country by using the drop down selection at the top of the form. You can view the results for a given province, state or county as applicable by clicking the abbreviation on the left column.
At the bottom of the screen is the data controller. This can be used to search your store database.