I started with this kit myself, but I wish I had gone with a proper enclosure from the start, like the one I'm building now. Seeing as you already have it and it was free make the best of it. I got mine to where it will function properly.

First off, besides the kit you will need:
2 Hides - The one that comes with it is too large for a small BP.
Thermostat
Under Tank Heater
2 Digital Thermometers with Probes
Humidity Gauge - Preferably Digital
Large Strip of Carboard
Aluminum Foil
Duct Tape

Place the Under Tank Heater under one side with the thermostat probe between the UTH and the glass, I use the right side of the tank. Place on of the thermometer probes on the inside of the tank above the thermostat probe. Place the other thermometer probe on the inside of the tank on the opposite side from the other. Cover the probes with the substrate, keep the substrate 1" thick or less, you don't want to block the heat too much.

I don't use the heat lamp that came with the kit anymore, I only use the night heat bulb. The UTH works during the day to keep it at the right temps and at night when it gets colder I turn on the night lamp, then turn it off in the morning. Keeps the temps just right 24 hours/day.

Now for this to work properly you need to do 2 things. Cover 3 sides of the tank in cardboard for insulation and to help your BP feel more secure. You can even find an aquarium background to go between the tank and the cardboard to give you scenery. The second thing you need to do this mod to further help control the heat and to regulate the humidity properly. http://ball-pythons.net/forums/showthread.php?t=90187

This isn't the only way to do it, but this should get you going on a good start, read the directions for the UTH and thermostat.

Here's how my setup ended up.



P.S. : Welcome to the site. Pay attention to the advice you are given, there are alot of people here that will save you some headaches and help you keep your BP happy and healthy.