What is the burden on an appellant to affirmatively show that error was committed by the trial court?

"It has long been settled that the burden is on an appellant to affirmatively show in the record that error was committed by the trial court: '[I]t is settled that: "A judgment or order of the lower court is presumed correct. All intendments and presumptions are indulged to support it on matters as to which the record is silent, and error must be affirmatively shown. This is not only a general principle of appellate practice but an ingredient of the constitutional doctrine of reversible error." ' " (People v. Alvarez (1996) 49 Cal.App.4th 679, 694; italics omitted.)