Right-click the existing B&GS.rar and choose "Open with WinRAR."
If you do not have WinRAR, 7-Zip can create .7z files, or use the "Add to archive" function to create .rar files if the RAR plugin is enabled. B&GS.rar
In the WinRAR "Add to archive" menu, check "Create solid archive" for better compression, particularly if the files are similar. Right-click the existing B&GS