I am flying on Wednesday but there is one stop, does that mean i am changing planes

Not necessarily. Ask the gate agent when you check in if you will need to change planes in your stopover city. You may be on the same plane with a brief layover or you may need to depart the first plane and go to a new gate after the first leg of your flight. Your bags will be checked through to your final desitination either way.

Janet,

If the flight number is the same for both legs, you will most likely be on the same plane and would be able to stay on board (or get off to stretch your legs if you like). If the flight number is different, you will be required to deplane, even on the off chance that you're physically flying out of the same gate on the same plane. You didn't mention which city your stop is in, but if it's one of Delta's hubs, the distance between gates could be significant. If your stopover time is short (less than 45 minutes or so), you may want to try on line to get a seat near the exit (near the front of coach). You can also determine the gate plan ahead of time by checking on Delta.com and can see most of the hub airport diagrams on line or in the Sky magazine on board. They do change gates frequently, so be sure you double check as soon as you deplane.
Good luck!