When we hooked up a used whirlpool gas dryer and turned it on we started to smell gas is this normal? I don't want to blow the house up.

No, this is not normal. There is obviously something wrong with the way it was connected up. One of the connections is not properly tightened. Do not use until the connection is fixed. Turn off the gas in the meantime so your house does not explode due to the gas build up.