You have the "red" dipstick? The real long one with a black plastic tip marked at 25 and then farther up at 80 Celsius.
If not anything will do. Cold in park the fluid is up the dipstick about one inch; When warmed up the fluid is up the dipstick about two inches.
Start the car, leave it in park and measure the fluid. It will be about one inch up on the black tip. Let the car warm up to normal operating temperature.
Get in the car and move the transmission through the gears manually, then place the car back in park.
Measure it again. If you are near the 80C mark you are good to go. It doesn't need to be exact, give or take a little is fine.
If you need to add some, put it through the dip stick tube and use Pentosin ATF 134