There are a few steps you can take to install .NET Framework on your PC. First, check to see if your version of Windows supports .NET Framework. If it does, you can download the installer from Microsoft's website. If it doesn't, you can try using the Windows compatibility tool to check if your version of Windows is compatible with .NET Framework.
If your version of Windows is compatible with .NET Framework, you can download the installer from Microsoft's website and follow the instructions to install it.
If your version of Windows is not compatible with .NET Framework, you may need to upgrade your version of Windows. You can do this by downloading the latest version of Windows from Microsoft's website and following the instructions to install it.
Once you have installed .NET Framework on your PC, you should be able to upgrade to Windows 11.