if you are installing NOW, i suggest you download and install GoAutoDial instead. Later version of the same software (available at GoAutoDial.com, free!)
You may also want to consider Vicibox Redux (available at Vicibox.com, free!).
If you require CentOS or the "pretty" agent screen included in VicidialNOW, you should use GoAutoDial. If you do not require either of these, you should use Vicibox Redux (created by The Vicidial Group, the owners of the site you are on right now and the maintainers of VICIDIAL, the actual software that IS the dialer).
BOTH websites have walk-through instructions on how to install.
g729 is a licensed codec. So you can purchase that from a reseller (digium.com, for instance) or you can look on the internet for a location to download it elsewhere. This is an ASTERISK function which is in no way related to Vicidial (so if you get instructions on how to do it from an Asterisk forum or site, it will work, and you'll be able to use it on whichever system you installed because they ALL use Asterisk
)
If you want to continue with VicidialNOW, you should download and read the free manager's manual from EFLO.net (and seriously consider purchasing the paid version, it has a lot of tips and tricks in it!)