Bad connection at battery?
Assuming you are working on the 66 dart in your bio tagline. Assuming slant six since it is posted here. Get the car into a safe spot where it will not roll. If it is a manual put it in nuetral and block tires so it doesn't roll, if an auto put it in park.
These instruction assume knowledge of using a test light. Attach test light to battery ground terminal and touch probe end to small terminal on starter. Have assistant turn key to start. If it lights your starter is the problem. If it doesn't light time for more diagnosing. This is usually the part where I would use a screwdriver to bypass the crank circuit and spin the starter. to do this
Once again make sure car will NOT ROLL when it starts nuetral/park. Turn key to run, use screwdriver to make contact between the big terminal on the starter and the little terminal on the starter. If your battery connections are good this should cause the starter to spin the engine. With the key in run it should also start allowing you to drive to a more convenient location. When making contact with the screwdriver do NOT touch any part of the car or starter besides the 2 starter terminal. The big wire from the battery has a lot of energy and will instantly weld itself to any grounded piece of metal which can blow a battery up or start fires.
Here is a link to a picture of a starter in case you are unsure. You can see the two terminals in the picture.
http://www.ebay.com/itm/82-83-84-85-86- ... es&vxp=mtr