Congratulations 
To release it on stable you can use snapcraft release nsm $REVISION stable where revision number is the revision the store assigned your snap. See snapcraft list-revisions nsm for the revisions available to release. There’s a doc page here for this process: Releasing your app
Alternatively, you can go to snapcraft.io/nsm/releases and use the GUI there to do the release. See Release management and Using the Snap Store for some examples of how to use the snap store management pages