help! convert sheet music to tabs

Hi,
It's not as automatic as that.
What you can do:
1. Select the two piano staves, then in the "Tools" menu -> Implode
2. Copy the result (from the first staff) and paste it into the guitar staff.
3. The problem is that, as the piano doesn't share the same clef as the guitar (8vb), you'll need to select everything and then press Ctrl + arrow to change octave.
4. But the biggest problem lies elsewhere. Unless the piano score is really simple, you'll have to make a guitar arrangement, in other words, make choices (deleting certain notes, for example), and perhaps transpose, to make things easier.