My pool is Intex 15x42.

The hardest thing I am learning is chemistry, once I get the salt level right do I need any other chemicals? Water looks crystal clear right now but only been up one week.

Your swg will generate chlorine from properly salinated water.
Your manual will tell you how many PPM (parts per million of salt you need.) My swg calls for 3000 - 3500 PPM as an example.

Use pool salt, you can buy it at Home depot, walmart etc, $6-7 per 40 lb bag.

You will need also a way to reduce your PH, swg will tend to increase PH quickly.

You can use muriatic acid in liquid form or PH reducer in powder form. Both do the same thing.

You will want to shoot for:
Chlorine 1-3 PPM (I keep mine closer to 3 PPM)
PH 7.2 - 7.8

You will need to run the swg as needed to maintain that level of chlorine, and add ph reducer as needed as well.

I recommend you test the water daily for the first week, the twice weekly for a few weeks and once you have it down, weekly.

Also be aware in a small pool , the sun will deplete chlorine very quickly, so you can add some stabilizer to help protect the chlorine. A pool store can help you with that.

Good luck!