See the top radiator hose? Follow it to the engine. In your picture one of your heater hoses (there are 2) is just to the right of the top radiator hose. Bout 1" or so in diameter.
Follow it back to the firewall and you'll see the other one, running from the engine to the firewall too.
Disconnect both hoses at the engine after you finish flushing out the engine.
Run water through both heater hoses, one at a time, to flush out the heater core.
Reinstall the hoses, let the water drain out, fill with coolant/antifreeze. Leave radiator cap off, start engine and let it idle for a bit, if possible with the front of the Jeep slightly higher then the rear. This will allow any trapped air to bleed up and out of the system.
While you wait, pop the hose from the radiator that runs to the overflow tank.
The tank slips out of it's bracket, once off flush it out too. Reinstall it and add coolant/antifreeze to the proper line, reconnect the hose to the radiator.
After 5 minutes or so your system should have the air bled out, top off the fluid, install the cap and check for leaks. Clean up the mess, dispose of any old fluid properly.
Antifreeze/coolant is poison to small animals and kids.