Know how to turn off the gas supply to your dwelling. If you smell gas you have a leak somewhere, vent the area immediately, Turn off the gas. Before working on gas appliances, turn off gas and open a valve to clear residual gas from the lines. Try to avoid disconnecting brass connectors on the flexible gas line. If you do, when reconnected and gas has been turned back on, carefully test the connections with soapy water dripped on the pressurized gas line and fittings.
Bubbles mean a leak.
Retighten or replace. Gas connections can be dangerous. If you are not comfortable with your work then you should have a knowlegable expert check the connections. Often the gas company will do this at no charge. Be careful, use common sense, ask for instructions, don't hurt yourself, but if you do, Appliance Helpline is not at fault.