Setting different permissions for a Shared Documents folder

Hi,

I'm trying to set a Shared Document in our SharePoint 2010 with the following permissions:

Root Folder --> Only Owners can make changes

└----> Sub folder 1  --> All users can make changes

     └----> Sub-sub folder 1   --> All users can make changes

└----> Sub folder 2 --> All users can make changes

     └----> Sub-sub folder 2  --> All users can make changes

How should it be done?

Thanks!