A little "copy 'n paste" from the web:
1. Pull out the dipstick.
With the gearshift in Neutral or Park and the parking brake on, let your engine run. Be sure the engine is warm when you pull out the dipstick. (Don’t turn off the engine.)
2. Check the fluid.
Dip the tip of your index finger into the fluid on the dipstick and rub the fluid between your finger and the tip of your thumb. The transmission fluid on the dipstick should be pinkish and almost clear. If it looks or smells burnt or has particles in it, have a mechanic drain and change the fluid.
3. Wipe the dipstick with a clean, lint-free rag; then reinsert it and pull it out again.
If the transmission fluid is clear but doesn’t reach the “Full” line on the dipstick, use a funnel to pour just enough transmission fluid down the dipstick tube to reach the line. Don’t overfill!