Printing Barcodes Using Php And Use The Current Format Follow

I've not had any experience with PHP myself, but I'd recommend making use of the Integrations Platform in BarTender 2016 with web services.  See the below white paper:

http://www.seagullscientific.com/media/101724/bartender-integration-builder-201511.pdf

This forum post should also prove helpful:

http://forums.seagullscientific.com/index.php?/topic/4481-how-to-integrate-bartender-with-php-via-web-service

I think im getting something. BTW what is the .dat file?

I see that bartender can read the data in .dat file which will be used to the labels.

But how to create the .dat file is there a documentation to it? and how to assign it to the labels? 

A dat file in this respect is just a simple text file that contains data.  You can use Notepad and save as with a .dat file extension.  Typically this would contain delimited data of some kind.