First: You need to go to the Optifine homepage. https://optifine.net/home
Second: Click Downloads.
Third: Pick the Minecraft version you want it in.
Fourth: Click Download by the version.
Fifth: Then something called AdFly should pop up wait 5 seconds then go to the top right hand corner of your screen and click skip ad.
Sixth: Then in the middle of your screen it should say optifine then the version you chose .jar click that and save when it is done downloading click install and it installs it for you.
Second: Click Downloads.
Third: Pick the Minecraft version you want it in.
Fourth: Click Download by the version.
Fifth: Then something called AdFly should pop up wait 5 seconds then go to the top right hand corner of your screen and click skip ad.
Sixth: Then in the middle of your screen it should say optifine then the version you chose .jar click that and save when it is done downloading click install and it installs it for you.