How to install Optifine for minecraft?

I downloaded it before but now whenever I try to download it, it doesn't work for me. I click download on the optifine I want but whenever I try to open the jar file, it's just like a link that directs back to the optifine website. I don't know if there's some software missing or something, but the optifine file that I download isn't even like a jar file, it's more like a link back to the website.

Guest

I used this:

FLASH

Then call 101 and tell them that minecraft forge doesn't install optifine.

Mohammed