Just start the engine, pull the transmission dipstick and wipe it off, re-install it, pull it out and look at the level of the fluid. It it is spotted all over the stick let it run a couple of minutes with the stick out and wiped clean and them install, remove and inspect the level. It should be near the add level if cold and near the upper range if hot. If the fluid barely wets the end of the dipstick, or worse no fluid is on the stick, add a quart of Dexron and re-check the level. And if fluid is needed look at the radiator to see if transmission fluid is leaking at the cooler connections.