It has been a long time since I have used a similar hard disk recorder.
First, it helps to understand tracking, recording and mixing from an analog perspective.
A hard disk recorder (digital device) consolidates all of those features into one box.
On the VS-1824, I would suggest initializing the unit to its defaulit settings. Plug a mic or instrument into channel 1
and use the E-Z Routing
Understanding how the signal flows for tracking, recording and mixing within the VS-1824 for one track applies to all tracks.
Hopefully, someone who has extensively used one and/or is still using it will chime in with specific shortcuts.