Select the Forge profile in your Minecraft launcher to start the game with the mod active. Safety and Source Warnings
If you clarify what you're actually trying to do (e.g., "install a specific mod for Minecraft 1.12.2"), I’m happy to provide a clean, safe guide. jenny mod forge 1122v190jar nacharty na extra quality
Reduce render distance to 10, turn off “smooth lighting” in OptiFine, and allocate more RAM: In launcher → JVM arguments → change -Xmx2G to -Xmx4G . Select the Forge profile in your Minecraft launcher