If you can find an aftermarket kit, it should come with instructions. Check suitability for your car before buying.
Auto wipers do seem a good idea, but there are issues.
The sensing is not as clever as it needs to be. There are times when it wipes with hardly a drop on the screen, and others when you are nearly blind before it wipes. Normal intermittent is easier to tolerate, and you always have single wipe when needed.
If the sensor catches a fly, the wipers may wipe continuously until either they've scraped the goo off the screen, or you've stopped to do it yourself, or they've blown a fuse.
It is easy to forget they are on when you stop, if the rain is light and they have not wiped for a while. Then when you restart, they wipe straight away, even if screen is dry.
Had them now on a Fiesta for about 2 months. I'd rather not have them.