You should first go to the BP Husbandry forums and look for the sticky thread that shows proper tank setup. This will get you started on the right track. There are a lot of things that can be fairly easily modified, but you should start here first.

Your tank is almost all wood... most tanks/tubs use UTH (under tank heaters) but I don't see that as a good option for you, as heat isn't going to penetrate that particle board very well. I think for heat, your best option would be to look into a radiant heat panal (RHP). Probably something in the 80-120watt range for a tank that size, or maybe even better, two 40 watt panels. This would allow you to keep one side a little warmer than the other, giving you a hotspot on one side and cooler side on the other. With the radiant heat panels, you can set them on a thermostat, or maybe even a dimmer switch and just dial it in until you get the temps you want, then you're all set.

If you have a ball python, they like hides that are tight... that they can feel against their body when they're inside of it. You can buy these online, just search for snake hide or reptile hide. Just make sure it has an opening, and an open bottom, so if you lift it up, you can get to your snake. If you want to go cheap, you can get some colored plastic bowls and cut a little "door" into the side of them and there ya go. It is preferable if you have one on each side of tank, one on the warm side, one on the cool side. It's even better if they both look and feel the same to the snake.

That would be start... just keep asking questions and keep researching. People have made good homes for snakes out of far less than what you have here. Yes, it will take some work, and yes it may take a little more money, but it can be done. I guess you have to decide if you want to invest in making this tank work, or maybe just returning this one and buying one that is better suited for a snake. I would probably advise you in that direction, but i'm still pretty new to this as well, so hopefully others will chime in with more experience.

Best of luck!