Thought I may as well add a bit to this as I've been about 20-30 times over the years.
There's two big cart parks, just park up, buzz the door and they let you in. Pay your entrance fee and they will give you a towel and locker key. Wednesdays is naked day (they give you a small towel only) and Fridays is shemales day but you don't have to be one! Put all your clothes in the lockers at the end of the corridor and towel round your waist and go explore.
Ground floor has a restaurant/bar which does some nice food. Condoms, lube, poppers are available if you just ask the staff at the bar. Everything gets booked to your locker number for those bits. Also on the ground floor are showers, toilets, sauna, swimming pool, big jacuzzi, small glory hole room and a few other small playrooms that are usually empty unless it's busy. Theres also a room to put on makeup if you are CD/TV that is separate to the normal changing rooms.
The basement has a dungeon set up, it's pretty dark and usually the trick is try and close your eyes as you go down the stairs so your eyes adjust. There's a sex swing in there and usually someone waiting in it or bent over one of the other bits of furniture. In general you don't need to ask those people for permission if you want to fuck them but a quick grab of the cock or something first is considered polite.
2nd floor has bi cinema room, sometimes people are just watching together other times there is fucking in there. There's about 4 playrooms opposite that with lockable doors. In the middle is a dungeon setup with swing, saint andrews cross, large bed watching fetish porn and a watersports area (although I've never seen it being used). More toilets, showers, sauna, steam room and rest area. The opposite end has a gay cinema with the same setup as the bi one. Loads of playrooms, some are open, some can be locked and some allow locking but can still be viewed. If someone is in one of the rooms alone this 99% of time implies they are open to anyone joining them, just walk in and lock the door behind you.
Top floor has a smoking area and outside terrace. I've only been up there a handful of time and never seen anything other than people smoking/sunbating or just relaxing.
Best advice is try not to be nervous, most people are really friendly and take your time to have a look round and get your bearings. Most people would happily show you around if you mention you are new. This isn't a pay for play venue. Everyone pays the same to get in and what you do in there is free and always up to you. As a side note they also have overnight rooms if you are travelling far or need a hotel for work