Ok.
Look at the score and you will se that there are three voices superimposed in those bars. There is the bass (minims and semibreves), there is the top voice on the treble (crochets quavers and minims) and there is the middle voice (semiquavers) that forms the accompaniment.
You play both the top voice and the bass with the left hand, while the accompaniment in semiquavers is played with the right hand. In other words, you cross hands (left on top of the right).
Starting on bar 23, I use the third finger of the left hand in all notes, bass and top voice (but you can experiment with 1 or 2 and see what fits you better). Then on bar 26 I use 2(G) 3 (F#) and 4(E) of the left hand. On bar 28, I use 4(D) 3(E) and 2(F#) of the left hand for the top voice, but you may try 3 – 2 – 1 and see if you like it better. Same for bar 28.
Hope this helps.
Best wishes,
Bernhard.