Find the image you want to alter and right-click on it. Choose: "Open with > Adobe Photoshop." This can also be accomplished by first opening Photoshop, choosing: "File > Open" and navigating to the image.
Make sure the Image is in RGB Color mode by using the command: "Image > Mode > RGB Color."
Create a new layer over the layer you wish to alter and fill this layer with the desired color for the lines.
Find the pulldown: Layers Palette Blending and select: "Lighten > Screen > Linear Dodge." The image should take on the color previously selected.
Once you have achieved what you were looking for by using one layer or multiple layers if multiple colors were needed, flatten the image under: "Layer > Flatten Image" and then save.
http://www.ehow.com/how_6391009_chan...photoshop.html
Or you can just do what the people above said. My software has a button that does all the work, so I don't know much.