Question about coloring hair?

Okay, so I dyed my hair in Summer 2013, to a bright Magenta and red color....a lot of my roots have grown since. I get to dye my hair again in February, but Ive grown a liking to the color light brown for my hair instead of red (/.) How would I do this? Would I apply the light brown color directly on my red hair and just cover everything up? Or is there another way I could do it? (BTW, if have no money to go and color my hair at a salon, so that is out of the question) Any help?