Your ball python should have a constant hot spot of 90-95*. That being said, it shouldn't come from a lamp. You should get a under tank heater controlled by a reptile thermostat.
A heat lamp is not the way to go. It dries out the air and will make it harder for your ball python to shed. Get an under tank heater and some kind of temp controll. The under tank heaters can spike up to 115 degrees and burn them.
Look on Big Apples web site to give you an idea of what your looking for and cost. They have some of the lower end stuff that works just find that wont burn giant holes in your wallet.
A UTH should be your warm end heat source(make sure its controlled somehow). You can use the heat lamp to control the ambient temps but make sure you can adjust it. It will zap the humidity but you can tweak that. Follow up on your temps with a temp gun. You can monitor the snakes actual temp with this as well.
I have 3 diff tanks 1 that has a heat lamp all the rest have UTH'S. i have my heat lamp in one because one of my BP's has difficulty shedding from time to time and it really helps to keep it humid (about75-82%) if you place the lamp right over the water bowl you just have to fill it up every day or other day! Give it a shot see what works best for you!