You will probably have to do a few things but more info and a pic of your setup would help.

Without having more info here are some suggestions. Cover most of the top accept where you heat lamp is with acrylic or foil. Get a 100 watt CHE (ceramic heat emitter) or deep red (IR) bulb and a dimmer switch. Walmart carries dimmer switches on a cord for $10. This way you can dial it to where it needs to be just to warm the air. You will have to still monitor this carefully and some would suggest that it should also be controlled by a seperate thermostat.

You should also have a UTH controlled by a good thermostat (Herpstat or V.E.) for your warm spot. Set that so you have 90-92.

Now because this setup requires CHE to achieve good ambient/ cool side temps you will probably want to use cypress mulch or cocoa choir for substrate because they will hold humidity well and don't mould easily.

I would seriously consider the caging choices mentioned in the above posts. A good cage that is easy to clean and maintain will let you enjoy your snake.