DC Amps and AC amps are the exact same thing, they are the measurement of electrons past a given point, the difference is that the electrons of AC go back and forth (alternating) and DC go only in one direction (direct). Measurement must however be done with two different meters, if you measure AC with a DC ammeter it will twitch a lot but you'll get no reading, if you measure DC with an AC ammeter it might just let it's magic blue smoke loose and you will have a nice christmas tree ornament but no more ammeter. I imagine you have your genny hooked up to a rectifier then to a battery? If so, after the rectifier you should hook your DC ammeter up in series (one wire to the positive post of your meter from the positive post of your rectifier, the other wire to the negative post of your battery from your negative postof the ammeter or vise versa depending on the set-up), with the reading you get you should be able to just multiply the amps times the voltage of your battery and you will get total watts. If you aren't hooked up to a battery you can hook up your genny before before the rectifier to an AC ammeter and give it a spin, polarity doen't chane a thing, the problem witht this is that the amperage you get will be the short-out amperage and not an actual amperage of your specific genny on the pole, it will also be fairly hard to spin. You can get voltage tho.
Hope that helps,
LEXX