Newbie with Flexigrid

[eluser]ReyPM[/eluser]
Hi:
I'm newbie with Flexigrid(http://flexigrid.eyeviewdesign.com/index.php) and I'm trying to use in my site. I've downloaded all the files and copy to my system folder. Now what's the next step if I want to retrieve all the data from a table called "tbl_usuarios" and use to show the files? Can any help me? I've read the documentation but is not clear at all to me.

Cheers and thanks in advance