Share the score with who? To share a high score with other users of your game, the score needs to be posted to a database that your app can read from. Possibilities include a FirebaseDB, a CloudDB , TinyWebDB or a GoogleSpreadsheet on your Google Drive or you can send the score via Texting or an eMail with a specific individual.
A possibility
or How do I create a Leaderboard for a Game using TinyDB? - #2 by ABG
or one of these discussions might answer your question Search results for 'high score' - MIT App Inventor Community