How do you convert piano sheet music to cello sheet music?

The bass line can be read just fine by cello. Occasionally it will go out of range, but then you just play an octave higher.

If you mean you want to play the melody line in the treble clef, then the range will often be higher than would be chosen for a cello melody, so either learn to play the high stuff or take it down an octave or two.

There's no conversion that really needs to be done other than putting it in the clef you would rather read.

If you mean how do you turn treble into bass, if you read the line or space below, the notes will be the same but two octaves lower.

For example, the top line in treble is F, and the second line from the top in bass is F.

That's a quick way to do it.

Not sure what you mean. if you mean using the harmony, melody , or base line from a piano exert, than just copy it. Cello has the largest rage of any string instrument, so write it reasonable for a player to play. If you mean an accompaniment, then it's written in the base clef any it's up to you on how you want to pair the piano. Great combination if that's what you're aiming for. Good luck