[OpenLayers-Users] How to get information on clicking on a polygon

[kusum]

Hii All

I am trying to get information about a polygon from postgresql database when 
user clicks on it.
I have read get Feature info example in openlayers, but was not able to 
understand how they were fetching the data from database.

Can somebody please explain a bit or if there is any other example 
available.

Thanks in advance.
Kusum