How to start and refill water jugs at HEB?

Hi all!

I currently buy bottled waters, but I hate how much plastic I am wasting. I saw a water refill station at the HEB near my house and thought that might be a better way to get water. Do I buy a jug at HEB? Do they even sell them? Do I need to buy the same brand as the water machine or does it just fill anything? Do I pay at the cashier or at the machine? I know these are problems I could ask someone there, but I do have really bad anxiety, so the more I can prepare before hand, the better. Thanks in advance!