Prove that for functions f: R -> R, the epsilon-delta definition of continuity implies the open set definition

I have this written down.

A function f from R to R is continuous at a point p E R (p in R) if given epsilon>0 there exists delta>0 such that if |p-x|<delta then |f(p)-f(x)|< epsilon.

I don't know where to go from there...

Can someone help me out?