Adding mods to your Local Minecraft files (Client).There is another article available that goes through the process of adding mods to your modded Minecraft server. This covers steps to take when using the vanilla Minecraft launcher as well as a variety of modded Minecraft launchers. This guide covers all the steps to take when adding mods to existing modpacks on your home PC. If you play modded Minecraft there may be times that you want to adjust a modpack by adding mods to it.