It is possible that I am misunderstanding. You were asked to find the equilibrium concentrations correct?
so you should have an ice table similar to this:
HF(aq) ↔ H+ + F-
i 1M 0M 0.5M
c -x +x +x
e 1-x x 0.5+x
from...
What you have to remember is that ionic salts dissociate into their ions when in solution.
Consider the dissociation reaction of the NaF:
NaF → F- + Na+
Hopefully that should help you understand what to do.