Visit RARLAB to download the version of WinRAR that matches your system (32-bit or 64-bit).

Right-click the selected files and choose "Add to archive..." . Configure: In the window that appears: Change the "Archive name" to lathin.rar . Ensure "RAR" is selected as the archive format.

If you don't want to install software, you can use a web-based service like CloudConvert :