How do you re-solder wires to printed circuit board.?

First you need to make sure that your tip of the soldering gun is small enough to make good contact where you are soldering. Try and remove as much of the old solder as possible. Make sure the connection are clean this is a must. When you start to solder put the wire in place at the connection spot. Next put the solder gun on top the the wire to be soldered. When it gets hot enough touch the new solder where the gun and the wire meet. The solder will flow down the tip and onto the wire and the connection spot. Remove the gun but still continue to hold the wire in place until the solder cools. Hope this helps