I have dark redish/brown hair right now. I really hate the color and want to dye it light brown.

If I go get a box of dye from the store and do it myself, will it turn out an orangey color or will I be fine?

My hair is about medium length and healthy. What type of dye should I buy if this is possible?

Colour won't lift colour so buying a lighter hair colour won't get rid of the darker , might only result in making your roots lighter where your natural colour is! I would advise you to go to a professional salon to get it lightened! Box colours only result in a build up of colour in your hair which sometimes can be difficult to remove!

If you get hair color removel it will, but then when you dye it the color you want it will work. Trust me, I've tried.