Quick answer: on the Jam tab, press REC. The band starts from the top, you sing, and Stop saves the take to the song with its key, tempo, chords and groove attached.
Why not just Voice Memos?
Voice Memos is great at catching sound. It just doesn’t know what you were playing. Six months later you have “New Recording 47” and no idea which key it was in. A Porchtone take keeps the musical context with it, so opening the song puts the same chords, key and groove back on the Jam tab.
Meters, marks and takes
Twin VU meters show your voice and the band. Mark drops a marker at a moment you want to come back to. Toss throws a take away. In the Songs tab every take plays back with the band, ready to export.