How to do pink streak of hair?

my hair is layered, light blonde, but dyed. my natural color is a golden blonde, now its a light blonde. its about 3-4 inches past ym shoulder, and i just want to do like a 2 inch section underneath my hair. i only wnat it to last 4-6 weeks, so what should i use? and will it turn my hair a wierd color once it comes off if my whole head is dyed.