on the gui for the rtorrent, click on the "star" button to view the folder to create your torrent.
you will need to either upload to your whatbox using ftp or what you have already downloaded in whatever folder if any you have created.

in the box that opens, you will choose the location of your torrent, in the box below, u add your own personal announce url from what and then check off the box labelled 'private' torrent and press ok. and it should create the torrent.