I was wondering if I purchase these if there is anything else I need to do other than put them on. How can I put them on myself?

 

If you have a tire tool to break the bead of your tires then you can remove the valve stem and sensor and install the new one. Mounthem on your HHR and follow the installations in your owners manual to relearn them . You will need a tool for that
https://images.app.goo.gl/C99v8axNpYEM1bMv7