Hi!
Samsung pay should come pre-installed on your watch. You start Samsung pay by holding down the lower side button on the watch for a few seconds. The first time you do it, you will have to do the setup, which you follow the steps that appear on the watch and in your phone.
Should you have problems with this, you are welcome to write here again or contact our customer support for more help: http://spr.ly/6186DctJp
We hope this helps you!
/Daniel
