How do i place a block so that it appears below the page content and not above it? so its centered but below the page content?

A search on this site for this would reveal several answers in the FAQ section that may be of help (remember search is your friend):

* How to set a block underneath a module?
* Why do blocks always appear above the content of a module on its index page? Can I change this?
* How does the theme work in relation to the rest of the system?

Basically it depends on your theme design, and then the settings for which blocks appear on what pages. Just because the blocks are categorized as left, right, centerCenter, centerLeft, and centerRight doesn't mean that left blocks couldn't go right or vice versa just by a simple change in your theme file.