This tutorial is on how to make things damagable - which doesn't mean to just destroy them but to get proper debris, like a wall that afterwards has a crack in it or a hatch where after explosion only some parts are left - and now we will make a door!
some basic room with a cracked door in the middle. It should look
like debris after an explosion. If you like to then place some light
or just compile it without lights when this is finished. It should
look like this (don't care or the blue arrow at the moment):