Once you know the UN Document Symbol for a resolution, e.g. A/RES/62/24, you can use the Voting Records database in the UNBISnet-Voting Records database to discover which countries voted for that resolution.
If you do not know the Document Symbol, you can search for Voting Records on UNBISnet by using some Key Terms, e.g. "Non Proliferation Iran".
Consult the following section of the UN Documentation Research Guide: