When building your apex forms, logically grouping like inputs really helps the user along. Here where fieldset comes into play...use fieldset to group like inputs together to help navigate the user when entering data in.
For example...lets look at personal info. Grouping the name inputs and the address inputs will help guide the user along and give a plesent experience.
The code is actually pretty simple and can be incorporated into either a region or template. Just add the following to your header/footer sections of a region or just drop into the template for a region, report, just about anything.
<fieldset>
<legend>Fieldset Title</legend>
<input .......... (your code/report/anything here)
</fieldset>