After visiting a few directory to submit our website i notice they are asking for the link back which i don't have a place in our website to add their link so i was think to find a good php script to install in our website so what do you think do our website need a directory ?
Any directory asking for a link back is probably amateur garbage. You don't want to be listed more than a few high quality directories.
In general you go by age. Most of the directories that have been around 10+ years as a directory are of good quality trusted resources. I can't promote my own sites but a couple of other 10+ year directories that are accepting submissions are Goguides and Joeant.