Open the Songs drawer. The buttons along the bottom import songs from files, from the web, or you can create a new one from scratch.
In each case, the songs will be added to whichever Book is shown at the top of the drawer.
New Song opens an empty song page. Fill in the title and the lyric text, then save. If the song list is a book you created, the new song is added to that book.
Import Songs offers three choices:
A file can be .sfp, .sfb, .pdf, .txt, .cho, .pro, .chopro, .chordpro, .crd, .tab, .onsong, .sbp, .sbpbackup, .backup, .onsongbackup, or .zip.
Backups/exports from some other apps can be imported, for example OnSong or SongbookPro.
Text/ChordPro songs can be edited and customized. PDF songs can be cropped, but the content stays in its original layout.