I downloaded a shaderpack from this site: https://minecraftshader.com/bsl-shaders/.
I saw that software is needed to run inside of Minecraft and OptiFine. I downloaded that too but I can't open it.
It seems that it needs another type of software to open the optifine.jar
file.
I already tried installing WinRAR to see if it fixed the problem, but I didn't have any success.