First of all, decide where the wire has broken from, to be sure you are reconnecting it to the correct place. Then, find a similar gauge of wire, and either a couple of through crimps to fit. At a pinch, you could use simple screw connectors. Joint your short bit of wire, to the end of your red wire, the other end to the other breakage.
If you are unable to manage that - take it to a garage, and pay them to sort it out for you.
If you are unable to manage that - take it to a garage, and pay them to sort it out for you.

