Question about soldering
If you have any flux you should first add that to the pad, but this isn't entirely necessary.

Add a small bit of solder to the metal pads, then lightly coat tip of the wire with solder as well. 

Next, place the wire up against the pad and heat the wire and and pad with the iron. As soon as the solder melts, push the wire completely against the pad so it is making a solid connection. Remove the heat, and hold the wire in place until the solder hardens. 

Things to remember:


It is important that wire is completely up against the pad and not
making the connection through the solder alone. 
Don't keep the soldering iron up against the pads for too long as it could overheat
and damage the components already on the board.
The solder is holding the wire(s) in place, but you can add something like hot glue over top of the connection to prevent the wires from pulling away too easily.
Use a continuity tester to check the connections of each wire to pad and ensure you did not short any pads together.
As stated by Kaz, using a set of helping hands is a good idea. It can hold the wire to the pad, allowing the solder to harden completely undisturbed.