Hey so my sister has a 2006 Tl and wanted to update the Navigation system, but is not Tech savvy, i founf this website and wanted to see if it was a legit website for her to purchase the updated DVD...

The Official Acura Map Update Site | Acura | 2014 Orange DVD Map Update v3.D0 | HERE

Again, shes not tech savvy and cant hack the Navi herself. She has the 2009 Navigation DVD in there.

 

That all looks correct.
The 2014 DVD is the latest one for the '04-'06 TL models, and that's the lowest price for a new disc.

Your sister will need to eject the old NAVI DVD from the trunk-mounted drive and replace it with the new DVD.
She should have the NAVI code ready to enter once the new DVD is inserted.
It's a straight replacement and self-update, so no hacking or manual steps are required for the new disc to operate (other than entering the NAVI passcode).

Welcome to AZ.