How could I become a better long distance runner in track?

Focus on your breathing that way you will be able to go farther at a longer period of time. First the breathing then, you can focus on your speed

Breathe through your nose the entire time. Play a song in your hard and keep pace to the beat or rhythm. (Preferably slow song) drink lots of water. Double your intake on water. And always rest. Not get lazy but rest.

thanks Shila and you see I gave a fuck once

Practice running long distances.