Install Optifine with Java?

I have a problem with Java.

More precisely: I want to install optifine for Minecraft and have seen that you need java for this. So I downloaded it.

Then I downloaded Optifine from optifine.net. N friend of mine said the symbol of what you downloaded should be a Java symbol (this coffee cup). Instead, the symbol looks like this:

And when you open this file, "Express Zip" opens.

Do you have any idea why that (although I have Java installed) doesn't work?

If you have any questions, just write in the "answers"!

You may have downloaded malware. Do not run! Otherwise right click -> open with -> Java. What is the extension of this file?

Is the .jar in the zip directory?

The optifine file has the extension .jar

Where can you see that?

Well, it's not malware or anything. Then just right click -> open with -> Java.