Open PianoBit → Library → Explore and search for “Piano Sonata No. 10 in C Major, K. 330 (2nd Mvt - Andante)”, or import the file you downloaded above.
Slow it down to 30–50% and practice each hand on its own.
Use Stop & Go mode: the music waits until you play the right note — on screen, on a MIDI keyboard, or on an acoustic piano through the microphone.