So I've gone through the correct website and I've installed something that is called Forge-1.15.2-31.1.18-Installer.jar. I assume that is what it should be, but when I try to open it, a message saying " To use the Forge-1.15.2-31.1.18-Installer.jar" command-line tool you need to install a JDK". I have no idea what this means, I don't even know if I have followed the right method to install forge for 1.15.2. Could someone walk me through what I am supposed to do?
Thanks