GMod Custom Entities in Hammer?

OK so for my gamemode I made a working entity. But I’m making a map for the GM and I want it to be in the exact same place everytime so I don’t have to use spawning commands.
How do I do this? do I make a custom FGD? If so how? It’s obviously possible or the people who did gmod tower and stuff could NOT have all of their stuff in the map in exact places everytime it restarts. thanks.

You can make a FGD if you want it to have the proper model/etc, otherwise you can just manually set the entity class using the object properties menu.

it’s lua coded. how do i import the lua code or whatever?

You don’t. The lua code must be running ingame when you go to the map. Just put the entity’s class into hammer.