how can i host a game for a few of my friends?

[wolfhart545]

as stated

[Neoony]

Either you have to set up dedicated server: https://wiki.empiresmod.com/Dedicated_Server_Setup

This will run separately from the game.

Or you can create a server with "Create Server" in main menu and this will host the server within the game while also playing.

However both methods will require you to port forward your ports.
Its no different from any other source game, so pretty much any guide you find for any source game will work, just for different application/game.

For port forwarding, you can for example check this gmod guide, see section port forwarding:
https://steamcommunity.com/sharedfiles/filedetails/?id=179569412
So that people can actually connect to your server from the internet.