Whoever you order your parts from, get a ball valve (black handle on the silver valve) and install that on the end of the hose with a coupler on the inlet and a plug on the outlet.
Install a coupler on the inlet of your guns and surface cleaner so you can connect quickly.
The surface cleaner needs to be moving when you open the ball valve or you can make permanent crop circles like in the pictures above, when the surface cleaner is sitting in one place, it is cleaning harder and harder into concrete and if the concrete is a little or a lot weak (like a lot of concrete these days) you will have permanent etching that will not ever go away. Slowly start walking as you open the ball valve or pull the trigger.
I would go and get insurance before cleaning anything, just in case.
Go clean concrete at friends, family and relatives' houses for your practice. When you understand what you are doing, can do a good job and do the detailing with the wand then it is time to go and knock on doors of businesses and houses and offer to do a free demo when you see some dirty concrete.
A free demo will help them see how dirty their concrete really is and it will give you more practice.
Good luck.