Buy a code reader for Ford, plug it in, then turn on the key and the codes should appear as described in the manual for the code reader. Usually flashing lights on the instrument panel.
The OBD II plug, that you need to locate before doing this, is right under the drivers side dash. Just to the right of the fuse panel. It's a black rectangular box, with a cover on it. A lot of parts stores allow you to use their ODB II, if you let them hold your license. I would try that before going to a dealer, or mechanic.. they want like $20.00 USD just to tell you a code. It could also spit out a "Dealer" code, which are generally in the 1000's, and most quick lube, and mechanics don't have listings for these codes, being that they are specific codes, for the dealership. Their way of trying to get more money out of you. If you find a nice OBD II scanner, it will tell you the problem on the screen, and manuals aren't needed.