Automatic transmission fluid

[cyberpor]

I found trace of dark red (brown) oil on the floor underneath the car. I believe that's automatic transmission fluid. However, the car runs find without any jerking when gear changes.

I studied the user manual to find where I can check its level but nothing there in the manual.
Could any one advise where to I check the level of the fluid, please?

Thank you much in advance.
Paul

[lawnmower]

some cars have a dip stick/filler cap in engine bay, some dont. Mines one that doesn't. I wish it did!