Where do I start measuring to place rod when hanging 84" curtains?

Where do I start measuring to place rod when hanging 84" curtains?

Hi, Rotts!

Do you mean 84" wide or long, please? Also, what specific part of the window is one of the curtains going to cover? There are many different styles and ways that curtains can be hung, so it would help to have some additional, specific information in order to advise you the best.

Thanks!