1) Install PloneSubSkins and SubSkins the usual way, by putting them in the Products folder and installing by going to: yoursite/prefs_install_products_form

2) Go to the control panel - SubSkins Setting  which will look something like this:

3) Start by setting another Navigation skin (to get the idea), press save and the look of the navigation portlet has changed.

4) Repeat for all the selections and you will have  a different look on your site, maybe like this... The red arrows show what selections does what.