Question about jar files [closed]

You are doing this wrong.

1. First off you need to install the mod loader for the mod, the most common are forge and fabric. Remember, this has to be the right version (eg 1.12.2 forge for a 1.12.2 mod)
2. After you do that you need to move the jar into your .minecraft/mods folder, on windows this folder is located in appdata.
3. Once that's done open the minecraft launcher and select the installation for the mod loader you installed. If it doesn't show up click on the installation tab and create a new installation with the mod loader version selected.
4. You may also want to allocate more ram by changing the advanced settings, I'd recommend you follow a tutorial for that.
5. Then press play, it might ask you if you want to play the modified version of minecraft, just click yes. That should be all the steps, you might need to install libraries for some mods so make sure you do that.