How do you check the transmission fluid?

If the car is an automatic, there should be a dipstick for the tranny fluid that will be labeled, "use automatic transmission fluid only". If the car is a standard then you have to get under the car and pull the drain plug and check the level there, and standard cars don't use transmission fluid, they use 902w gear oil. May I add, that you don't' check a manual transmission level by removing the drain plug. You check it by removing the fill plug. Also not all manual transmissions use the same lube. Some do indeed use automatic transmission fluid. Read you owner's manual. Also there are some A/T that don't have a place to check the fluid level. They are sealed for life transmissions.