having a mod means nothing basically.
you need some mods in your base to access some of the servers which use that certain mod. but they dont need to show up.
if you want to run your own server, your own game, even if its only with bots on your pc, and you want to apply a mod to it, then you have to go to the main menu, go to settings or set up, itk how it is in english, and the last chapter to choose there is called "mods"
then u just choose a mod and run it. your game will restart, so dont be confused or worried, just wait a second, and then u can start your game