how to change a thermostat in my jeep

You will need to remove the air filter housing and unplug the throttle body connector to access the thermostat. Before you remove the thermostat, drain some of your coolant, so it doesn't spill all over the place when you remove it. Do this by removing the radiator cap (while the engine is cold, otherwise hot coolant and steam will burst out all over your face) and unscrew the draincock at the bottom of the radiator to drain into a container (don't just let it drip all over the ground. Antifreeze is highly toxic and can kill cats and stuff.) Next, remove the upper radiator hose and thermostat housing bolts, swap out the thermostat, put everything back together, and refill the coolant. Check your owners manual for what type of coolant to use.

Here's a pic showing the location of the radiator cap and draincock.

Pic showing the location of the thermostat housing with bolts and throttle body connector. The torque spec on the bolts is 12 N-m, or 105 in.-lbs.

Pic showing the thermostat in the thermostat housing.