It can take a while for information from the database to sync with the Explorer map. If you've added a record store to the database, it will generally take about 5 hours for the store to start displaying in the map. In some cases it can take a few hours longer, but it will show up eventually.
If you still don't see the store you've added on the map after the given amount of time, please contact support.
Thanks for helping us build the world's most comprehensive database of record stores!