Mac: Download forge 1.8 (Preferably the lastest version) Download optifine 1.8 (Preferably the lastest version) If you want to download any more 1.8 mods, such as ToggleSneak, do it. Click the forge download, then click download client and wait. Open up Finder, then click Go from the top left side Type ~Library/Application Support/minecraft/mods Put those files in, make sure they're in .jar Open up minecraft, make sure you're in the Forge profile. Enjoy! :D I'll do Windows later on, sorry.
1. Download forge of the version you prefer, and install it. 2. Run your minecraft once, by then it will create the folder called "mods" in your .minecraft (%appdata%) 3. Download optifine of your preferred version, and put the downloaded file in your mods folder. 4. Run Minecraft, and it'll all be done.