Advice for fixing my horrible hair dye?

My friend, who is a hair stylist dyed my hair today, and it's horrible. It turned out to be horribly dark and she didn't even cover the back, so it's half dark purplish red, half light brown. I need to fix this myself probably but I was wondering if there was a way I could make it one even tone and also more of a strawberry blonde? Should I buy a lighter color with or without red in it?