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When i try to download optifine it downloads as a intenet explore file and not a java file
Check your File Associations; .jar files might not be associated with Java. Go to Control Panel - Programs - Default Programs - Associate a File Type.
"We live on a placid island of ignorance in the midst of black seas of infinity, and it was not meant that we should voyage far."
I guess you are using Windows 10, aren't you?
It basically doesn't matter what Windows thinks it is as long as Minecraft Forge does.
It should be called something like "OptiFine_1.7.10_HD_U_D3", depending on the version you downloaded.
Just copy it to the mods folder and you'll be fine.
Thank You so much