rocknbil - 10:35 pm on Jan 3, 2010 (gmt 0)

If you have to explain how to use a site, something is flawed in it's basic navigation or architecture. You shouldn't have to waste resources or real estate on how to work your site.

"2. A man from Mars can't figure out what your web site is about in less than four seconds." [webpagesthatsuck.com]

Exploring "how to use this site" would extend the four second attention span. I don't know that this would increase retention, I'd concentrate on the prime directive: make your content solve visitor problems, make that obvious in the content and links, they will stick.