How do i put transmission fluid in?

I hate to tell you, but during this period, Mercedes decided that you did not need a dipstick and made the dipstick a "special tool". You have to break the red cap off of the filler/dipstick tube, buy a dipstick (tool) to check the level, add fluid in that filler tube with a funnel, then put a new cap on the top of the filler tube. The easier way might be to bring it do a professional that has bought the "tool".