Get the Little Composers Piano from your favorite app store.
After you download the app, you should watch this video again and learn what the record, mentor and song buttons do. Use the help button (app menu) if you get stuck.
Make a few compositions and as soon as you find a melody that you like, turn OFF the record button, press the SONG button and store your composition.
If you don't want to make any more edits, then it's time to upload (publish).
Publish your composition
In "song mode", press the SCORE button to bring up a new screen and watch your melody turn to real music notes. Fill in your name and email address and press the UPLOAD button. Done!