To replace a gas stove, begin by ensuring the gas is shut off at the main valve. Disconnect the old stove, remove it, and clean the area. Install the new stove, connect the gas line, tighten the connections, and apply thread sealant. Turn the gas back on, check for leaks with soapy water, and ensure the stove is level. Finally, light the stove and check its operation. Contact professionals if needed.