Hi,
Simply use your previous flexibleVM2Global.css that you had before, we usually don't touch the CSS file much, most of the updates include only PHP file edits. (at least from v3.0 to v3.2, we didn't touch the flexibleVM2Global.css it has remained the same)
Once you get the v3.2 you will also get a plugin that is called "Flexible VM2 Template", install it to your joomla through "Extension Manager". Within this plugin, you will be able generate up to 2 custom TABs and you can put what ever you want in these TABs, you can even put some HTML code in it. You will be doing this through "Flexible VM2 Template" plugin.
Cheers.