In this video tutorial I show how to add a 2nd switch location to a single pole switch. It's a pretty easy connection, but you will have to run a 12/3 or 14/3 to the 2nd location depending on what size breaker is on your circuit. I am only showing the hookup not the actual routing of wire since all houses are going to be different. Here are some videos I did a while back to show some routing options:
https://youtu.be/_Q6BoHtu48w
https://youtu.be/7eiH2mJKcRA
https://youtu.be/66HYjaQl7Ew