Uploading and extracting

Many roms I upload come in a folder format I am not familiar with, containing winrar files of the same name but with different file types (eg. [filename].r01, [filename].r02, ..., [filename].rar) each containing the nds file, but it never works on my card. When I encounter an upload such as this I am unable to do anything about it except delete the file and move on, could someone tell me how these are supposed to work?

Open a new folder, extract all the .rar files into it, then extract the file from the first [filename].rarAbit of a long shot but it works this way, Works every time for me!