Modding is resource-heavy. A launcher must handle Java arguments well.
Before adding specific mods, you must install a "loader," which is the engine that allows Minecraft to read mod files. The two most popular choices are (best for large, classic modpacks) and (known for being lightweight and fast). To do this within SKLauncher: Open the launcher and go to New Profile sklauncher how to install mods
your downloaded .jar mod files into this folder. Modding is resource-heavy
Now that your loader is ready, you need the actual mod files ( .jar ). you must install a "loader