Permalink settings for user friendly hierarchical structures

Hi!

I'm trying to set the permalink structure:
/%category%/%postname%/

Take this site as an example:

http://fondamenta.biz/about/

When I click to the next page under about in the menu I get:

http://fondamenta.biz/our-company/

But I would like to get:

http://fondamenta.biz/about/our-company/

So that also the breadcrumbs follow the same pattern.

Can you please tell me how to set the permalink structure to accomplish this?