How to color over a background in Photoshop using multiply?

[xcoreFacex]

Ok so, I currently use Photoshop 7 and well lately I haven't been able to figure out how to color over a background using Multiply. When I try to color over it the colors come out transparent and I have no clue how to make it go from transparent to visible without having to take hours and hours tracing along the lines of the drawing with the color I want and not using Multiply, So if anyone knows how I might be able to do this please let me know ^^ Thanks.

 

[SoJo]

What multiply does is to look at the color information in each channel and multiply the base color by the blend color. The result color is always a darker color. Multiplying any color with black produces black. Multiplying any color with white leaves the color unchanged.I do not understand what you want to do... Add color to a black and white background? Color over a background so that it looks like a drawing? Change the colors in your background? ......???( I do not think that multiply is useful in these situations ) I could explain you but I do not know what you want. Add details.I am using Photoshop CS5.