You almost made it, only a few steps left to play the game. First you have to choose your date and the time. Times that are already booked will not show up.
Please note, that there are more available times on weekends and holidays. Then you have to select how many people you wann play with. The prices are shown next to the number of people and rooms or you can look them up (here). Please choose whether you want to pay via Paypal or on site. If you need an invoice, please tell us this in the comment field.