Need help with crosshair lines on line graph

[Jared Sams]

I have an image that's essentially a x and y axis with different lines on it. The lines represent different wire diameters. One axis is a wire feed speed in inches per minute. The other acis is the equivalent amperage. I want to be able to hover over a wire diameter line with cross hairs and have displayed the ipm and amps.  Anyone in here smart enough to help?