It is also possible to learn words in text from other applications such as your web browser, using the Windows clipboard. To do this, highlight the text with your mouse in the other application's window, then press Ctrl-C or select 'Copy' from the Edit menu. To actually read the words into Penfriend, open the Lexicon window and from its menu, select 'Learn Clipboard'.
This is particularly useful if you want to learn words from a web page or part of an existing document. If you want to learn words from a whole document it may be easier to save it as a text file and learn words from that.