Danny

This sounds a lot like a learning task assigned by a teacher so I don't want to just give you the answer.

The first thing to discuss is the fact that 'line' is not a good term to use since it is not a fixed or easily testable thing in Word. You should be working with 'paragraphs' instead of 'lines'.

To get started, try recording a macro of you applying highlighting to a selected paragraph of text. Once you have that minimal code, post it here and we can point you to how to start performing the other steps.

__________________
Andrew Lockton
Chrysalis Design, Melbourne Australia