I'll assume this is an ATX. You should check the fluid while the car is running, and preferrably after a short drive. If the fluid level is below the max line on the dipstick that's an obvious problem, but also check the color and smell of the fluid.
The fluid should be reddish pink in color on the towel and have a subtle smell to it. If the fluid is brownish and/or it has a pungent burnt smell to it then it has broken down and oxidized. If it has been like this for an extended period of time chances are there's irreversable damage and you'll need a rebuild. You can try flushing the fluid, but many people have found (and you can read more by searching) that flushing at that point will cause the tranny to fail right away.
I had my CD4E rebuilt last October, which cost me about $2200. I also had a broken mount which caused a lot of wheel hop which I suspect contributed to the damage, but anyway I digress. My fluid had not been serviced in 50000+ miles and when I checked it (as the tranny started acting up) the fluid was bad. I now plan on changing the fluid at regular intervals and spending the extra money on synthetic ATF.
