He may have only smoked once it's a little embaressing to say hey man I'm a stupid noob..... some people can't do that ..... so there are 2 screens....one for the bowl in your bong. or pipe whatever....it keeps ashed chunks from flying in your mouth.... the other as they said is used for breaking dope up.....but you can grind it too. anyway back to the BONG.
maybe the stem got pulled pushed and the rubber seal is bad...or lost it"s seal. get a new seal and stem...if the bong has a carb on it....a carb is a small hole you put your finger over while inhaling... let go of it when you are about to finish the hit then keep inhaling clearing the rest of the smoke... any other questions ask...I will see if I can help minus the attitude.....