Needing some help, first time snake owner.

Thanks again to everyone who has replied.

I do have an UTH heater for him but no thermostat (i'm working on that) so for now I have just got extra newspaper and things on top so it doesn't feel too hot to the touch.

There is a little pet store less than half a mile from my house. The owner is super nice and has a LOT of snakes. He breeds and takes in snakes that people surrender over to him. I took my little no name guy down to have the owner take a look at him because I was worried about a few spots on his scales and also he seems awfully small.
The owner confirmed my worries. He is "really underweight" but said the spots are only from previous bad sheds and should go away after a few sheds if I make sure everything goes smoothly. I told him how I had just gotten him but he said that I should try to feed him soon because of how thin he is so he sold me two rats and told me to not handle him at all tomorrow and then feed him on Saturday. He also said that's the reason he is so active. He is constantly moving back and forth in his cage like he is searching for food. I feel bad for him I want to feed him right away but should I wait so that he can spend a day in the tank warm and stuff before I feed him?

Again thanks for all the helpful tips everyone!

The UTH without a dimmer or thermostat won't necessarily feel "hot" to the touch....my UTH connected to the dimmer is over halfway DOWN and it stays at 90*.....without it it goes over 130*......you need that asap....

As far as feeding I'd wait for him to settle in a bit before trying to feed.

Alright, I finally got two digital probed thermometers for the bottoms, an air thermometer, a hygrometer, and a thermostat!

I still want to get some "decorations".. sticks and fake plants and rocks to make it all more natural.

Shew this poor snake I wonder how he has been staying alive this whole time with those people I got him from.

I am so excited to have this all set up right for him so that is comfortable now.

I texted them a nice message telling them all about how the "complete setup" they gave me was crap and how dare them try to keep a snake alive like that.
They tried to tell me, "You must be getting your information about how to care for one from someone who doesn't know what they are talking about because that tank was set up perfect for him. That's how he liked it. And you shouldn't feed him more than once every 6 weeks."

There's no use talking to people like that, as long as your setup is good now he should live comfortably. Congrats on your addition :D

Aww congrats on your first snake! I only have one as well, and am keeping him in a 20 gal long too. Good luck and at least from what you've said so far it seems like he's doing okay even though his previous owners weren't treating him right!

So I figured out that this screen on my 20 gal is part of the problem I'm having with humidity, and fixed that by placing a rubber hinged type glass aquarium lid over top of my screen. There is just enough screen still exposed to give him plenty of fresh air. My humidity is almost perfect now. I'm trying to eliminate the lights cause I've heard they can cause humidity problems as well, but even with my UTH I can't seem to keep the temp up. Should I look into adding another larger UTH for my hot side and use the smaller one I have for my cool side? The one I have says it's the right size for a 20 gal so I can't figure out why it isn't keeping my tank warm.
Anyone care to explain just how they keep their tanks warm?

THANKS in advance!