Right-click on the selected files/folders and choose "Add to archive..." (usually marked with the WinRAR icon).

If the files are too large, you can select a "Split to volumes, size" option (e.g., 1GB) to create a multi-part archive ( B&GS.part1.rar , B&GS.part2.rar ).

In the WinRAR "Add to archive" menu, check "Create solid archive" for better compression, particularly if the files are similar.