To change the position of the portal freely :
- use the dashboard feature : it is for any user to customize it's page
It also provide a drag and drop of the portlets in the pages.
look at it and customize more or less depending on what you need.

- use some layouts : several layouts can provide several "types of presentation" : with the same page, you can have several position of the regions in the page, therefore have several position of the portlets.
this is to provide a few different presentation/position of main portlets.

- use multiple pages, each are "quiet the same", but with portlets put in different region.

and of course, read the documentation, and look at the samples, to have see how all this work and what you can get out of each of these ways.

after, it depends on what you want, when saying "freely".

By the way if someone wrote interesting layouts, please think about contributing them :)