I've downloaded Arena and DOSbox and installed it all correct. I was just wandering if there was a way to play it in full screen instead of that small window.

Hit ALT-ENTER in DOSBox to go to fullscreen and back, or alter the line:
fullscreen=false
to:
fullscreen=true
in your arena.conf (or dosbox.conf, depending on how you set it up) file. This will make it start in fullscreen every time you run it.

Thank you. :foodndrink: