The following video outlines the primary rules of the sport.
This video illustrates how a ball that looks "in" may actually be "out", and vice versa. The take-away is that players should recognise that some line calls may appear ambiguous, and in all cases the call of the receiving side should be accepted, with grace.
The following video addresses the etiquette that should be employed when playing pickleball. For example, a ball from another court should be picked up, and returned to the relevant court, without disrupting any other courts where play may be in process. Simply batting the ball away from your court is not good etiquette.