can i put transmission fluid in my e430 or do i have to take it to a dealership. on 2000 Mercedes-Benz E430

i never had my tranmission fluid change, now my car will go in gear but will bearly move foward. i wanted to check my fluid level but the dipstick seems tobe seald.I also had some other work done to one time i could not put gas in with out it blowing back out. it was like a kind of back pressure.But i know that has nothing to do with my problem now.I need help!

Asked by for the 2000 Mercedes-Benz E430
Back to the dealer , its a mercedes , you bought now you have to pay..