So, I have downloaded Forge installer but when I open it the normal window does not appear, I'm always asked what to do with it, I can click on open but then I can only save the file can someone help me please?
You'll need to open the Forge Installer with Java.
If you don't have Java on your computer, you can either use Minecraft's built-in Java or install Java first.
So I have installed Java now, but when I open the Forge installer I get an error message "Java installation not completed. Java can't be installed" even though I installed it.