URL string

Hi,

maybe this is a really silly thing, but I´ve trying to figure out how to accomplish this for a couple of days with no results.
I want a section in my site to have different subsections of the form

/main-section // it displays last content submitted for each sub-section. For each subsection the URL will be:

/main-section/subsection-x // and it contains a teaser of nodes for each subsection-X (x=1,2,3...). Finally I want the full view node to have the URL:

/main-section/subsection-x/node

Well, and this is my approach on how to implement it: