Hello,
After you install the S5 Tab Show extension make sure you assign it to a position on the Template Layout sheet here:
http://www.shape5.com/demo/oasis/index.php/features-mainmenu-47/template-features/92-module-positionsThen in the options add input text for the # of tabs you want to have exactly and then assign it to your menu items accordingly. Then you need to create separate Custom HTML modules assigned to the s5_tab positions and add the content you need there.
I would suggest using a Site Shaper if you want everything set up ahead of time for you.
-Mike