Electric start question

hey everyone. Hope y'all are doing good. This is a two question question if that makes sense lol.

I grabbed a starter relay for a 78 xs650 of eBay. This will be a custom wiring job sense I bought the bike as a project. How do I wire this in?

Second question is about ignition coils. Are there after market ones like MSD or Accel?what can I get to replace the stock ones if all I can find are used ones?

Stater relay I bought

On the relay, a heavy cable from the positive post on the battery goes to one of the large posts on the relay and another heavy cable goes from the other large post down to your starter post. You need a switched 12V going to the yellow/red wire and if you are using the stock starter button the green wire would connect to the blue/white wire coming from the button. With the key on you have 12V at the yellow/red and when you push the button it sends ground through the blue/white into your green and completes the circuit, activating the relay sending power from the battery to the starter.
There are other coils available but you have to know what kind of ignition you have to get the correct ohm coil.

Thank you very much. I greatly appreciate the help on that.