Zenbeats includes advanced recording modes, like Recording to Timeline (which is a smart way to multitrack record any loops and song parts you have made over to timeline).
To access record modes, go to "transport" at the top of Zenbeats which displays the play, stop and record buttons. Here you can Right Click (or click-hold) the record button to bring up recording mode options. Select Record to Timeline, and start playing your loops. Press stop when you are done. To see what you have recorded, go to Timeline view for the linear recording of your song.