Solder the wires together.

Put a little bit of solder on the tip of the iron.

Hold the iron to the wire, and add the solder to the joint. When the wire gets hot enough, the solder will melt and suck itself into the wire.

Add enough solder and move the iron around enough to make the entire joint silver colored.

Once the wire is cool to the touch slide the heat shrink so it covers the joint.