MASSIVE BACKFIRING PLEASE HELP

I have a 1997 v6 camaro, 145,000 miles, and I am having major problems. I was driving down the street a couple days and I heard some loud clanking and then the car flat out died after one backfire. When I tried to restart the car the engine tried to turn over to no avail. I had it towed home. The next day the car starts right up and seems to be running completely fine except for white smoke coming out of the tail pipe. I drove around for a while and then stopped at the store. When I came back out the car would not start. Once again it would try to turn over and then just die out. After several tries I got it to start but with massive backfiring and smoke. Although it eventually died again. I know my catalytic converter needs to be replaced although I have a feeling that is the least of my problems right now. I dont have the ability to get the car to a diagnostic machine and I do not have any idea where to start. PLEASE HELP