How can i make a door ?

Hi ! i want to make my first mod in the 1.12.2 version (2020.2) and now i want to make a custom door but i can't found a good tutorial (i'm new with all of that)

and there is no door block base in this version.

i don't know how to make the rotation thing and how to make the block like the actual door in minecraft and not a full block.

Can someone help me ? ^^

Thanks !