Editing staff lines for educational purposes

Hi, I am writing a piano tutor book and would like to highlight certain staff lines (namely E & G in the treble and A & F in the bass). Can somebody suggest a way of doing this please?

Is it a case of exporting the extract to PDF and post-editing in Gimp? Or is it possible within Musescore?

I am wavering between using colour to highlight this area of the stave or maybe simply fading out the other areas whilst keeping them visible to the student.

I haven't actually committed anything to electronic form yet, so any tips greatly appreciated, thanks.