terrarium setup

up until recently, i've been on ssnakess.com & was told here that i'd received some bad advice on some questions i asked over there. 1 of those q's was about terrarium setup.
i know the UTH goes underneath, but where do the thermostat probe & thermostat go?
i'm gonna invest in a temp gun from proexotics.com so...yeah.
can i put the thermometer & hygrometer on the back glass of the terrarium or do they need to be on the sides?
i'm also planning on investing in a paper background to cover up the back & sides of the terrarium so the snake doesn't feel so vulnerable in the glass terrarium i have. i have a visionarium from creativepets.com. its got a little bit of screen on top, 3 glass sides & 2 sliding glass panels in the front. i plan to put a wet towel on the screen to keep the humidity in.
if i'm leaving anything out please tell me since i'm writing this all down.

The thermostat probe goes directly on your UTH outside the enclosure.

A temp gun is great for people who have rack setups, but if you are going for a single setup I wouldn't bother with a temp gun. Head to the home depot, lowes, or walmart and pick up the accurite weather station indoor outdoor thermometer. It costs about $12 and is the only thermometer/hygrometer you will need in a single setup.

You don't need to really "invest" in a paper background. I like using black paper or black foam core. This doesn't need to be expensive. You could even print your own background off the computer.

How big is this enclosure? If you plan on getting a baby snake then you will want to go on the small side.

A wet towel on the screen is not a good way to keep humidity up. Actually, it is a pain in the butt. You need to replace the towel daily to prevent mold growth and its just not really that fun to wash a towel every day just for a snake enclosure. Covering 3/4ths of the screen top with aluminum tape is a much better, more permanent solution.

I second everything Kaorte says, she knows what she's talking about. I only have 2 bp's but I use a temp gun in addition to my 2 accurite thermometers in each tank. This allows me to figure out the temps under each hide (hot & cool) & the ambient temp on each side of my enclosures. The temp gun will give you an accurate temp on top of the substrate, which is exactly what the snake would be subjected to. You can pick up a relatively cheap temp gun at most auto parts stores, the ones made for reptiles are really no different, probably just more expensive. I borrowed mine from a friend & little does he know, he's NOT getting it back haha. It's really so convenient.