In this step, you're going to heat the solder pad and the resistor's end cap so that they'll readily melt the solder wire.

Press the tip against the second R4 solder pad and the resistor's second end cap for a few seconds to heat them both. Angle the tip so it has maximum contact with the pad and cap.

If you heat them continuously for more than 10 seconds, the excessive heat may damage the solder pad or resistor.

Feed the solder wire into the heated area until there's a small glob of solder surrounding the end cap.

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