1992 Chevy Lumina wont start

hjhj I do not have a good knowledge about cars, but I need help. I have a 1992 chevy lumina, 4 door v6. I can't get the car started. The car use to try to do sumthing but didn't work. Now the car wont try anything. I know that i'm getting gas, b/c when i push the valve, gas came out. Someone told me to take a iron bar and tap it a little a couple of times but it didn't work. I change the battery but nothing happened. pleeze help me.