1997 Concorde won't start?

I drove the car to the zoo yesterday and it ran fine, however when I got ready to leave it started up and then went dead. I tried to start again but it only turns over but will not start. It was low on fuel but not out, so I added another gallon of gas and it still won't start. Also it is sitting with the front end down hill a bit. I have checked the fuse inside the car and the relay under the hood. I don't know how to check the relay to see if it's bad or not?