Press the tip against the circuit board's solder pad and the resistor's lead for a few seconds to heat them both. Angle the tip so it has maximum contact with the pad and lead.

Feed the solder wire into the heated area until there's a concave pool ("mini volcano") of solder surrounding the lead.

Remove the solder wire first, then remove the soldering iron from the pad.

Repeat this process for the second resistor lead.