Right sidebar example
The right side bar should be used for related content that is secondary to the page content:
The right sidebar may also be used for supporting content that directly relates to the preceeding page content:
Left sidebar examples
The left side bar should be used for sub navigation or filters. Visualise the content flowing from left to right, with the selections on the left filtering the content to the right.
My account council tax menu:
Map address lookup and filters: