Close. The yellow cord already has a 30 amp male to plug into the pedestal at the campground. You only use the provided black adapter that you already have if you want to plug into a 15 or 20 amp outlet at home.
Picture your old TT with a 30 amp cord that was permanently attached. When you grabbed the male end and pulled the cord out of the side of the trailer you were holding onto a 30 amp male plug. Your missing (yellow) cord also will have a 30 amp plug on it.
The only difference between the 30 amp cord from your old trailer and the missing (yellow) 30 amp cord from your new trailer is that the cord is detachable on the new trailer and permanently attached on your old trailer. Other than that they are the same.
If you look at the earlier post from RoyB with a picture of the outlets in a campground pedestal, you will be using just your yellow cord and plugging it into the circular black outlet that is just to the left of the 15 amp household outlet.
