Black Lines on my monitor

[P Tyrrell]

Hello - Help

About two weeks ago I noticed that there was a shadow appearing on the
monitor alond any black type or dark picture - thinking it wasthe monitor I
swaped it with another and there are still black lines appearing along the
lines of text.

What can I do to get rid of this?
Please bear in mind youre talking to a layman not a professional techie.
thankyou.

Paul