To check transmission fluid level, park the car on a level surface and then start the engine. While stepping on the brake, shift the transmission through each gear setting, then put it in park. Set the parking brake, then raise the hood.
Locate the transmission dipstick, pull it out from its pipe, and wipe it clean with a rag or paper towel. Reinsert the dipstick into the pipe.
Pull the dipstick out again and check the transmission fluid level. If the level doesn't reach the "Full" line on the dipstick, top up the fluid until the "Full" line is reached. Do not overfill.
While looking at the dipstick the first time, also check the quality of the transmission fluid. If it has a burnt smell or particles in it, take the vehicle to a mechanic for a transmission oil change.