When i am ingame in dungeon keeper 1 there is a black border on the top and the bottom of the screen. Every youtube video i've found doesn't have these black borders so i know they are no supposed to be there. How do i fix them?

You are probably experiencing some issues with the DOSBox configuration. I'm not sure how to correct the problem, but you may want to try with different DOSBox settings (an appropriate tool should have been installed with the game).

Anyway I suggest you to install KeeperFX for a better gaming experience: follow this guide.

in your DOSBox configuration, change aspect=false to true;