Picture. I just hooked up my dvd player to the tv and tried to watch a dvd. The picture comes up

Question

I just hooked up my dvd player to the tv and tried to watch a dvd. The picture comes up but it is still letterboxed. How do I get it to fill the entire screen? It looked like it was all strecthed out. I tried switching the aspect ratio but it didnt do anything. Should I try to adjust the setting on my dvd player?