Find the reduction and oxidation reaction and put it together
Oxidation: Zn(s) --> Zn2+(aq) + 2e-
Reduction: Cu2+(aq) + 2e- --> Cu(s)
So the redox reaction would be:
Cu2+(aq) + 2e- + Zn(s) --> Cu(s) Zn2+(aq) + 2e-
Cu2+(aq) + Zn(s) --> Cu(s) + Zn2+(aq)