Set up a new folder in your resources folder, for example, "map_mod".
Inside map_mod, create a new folder named "stream".
Create a new text file and name it "fxmanifest.lua".
Paste the following contents into your fxmanifest.lua file:
fx_version 'cerulean'
game 'gta5'
lua54 'yes'
this_is_a_map 'yes'
Move any game asset files into the stream folder to ensure the files load properly.
Make sure your new resource is included in your server configuration file.