jQuery Grid Plugin - jqGrid

Hi, 

I am new to JQGrid, I want to know how the add, edit, del buttons work. Right now I am passing a json string to a JSP file which has the code for the JQGrid. I use scrptlets to call my backend Java class which returns a JSON string. Then I pass this JSON string to the JQGrid and it works fine.

Now, I want to have the add, del and edit functionalities in my grid. When I click on lets say an add button of the grid, it asks me for a URL.

Does anyone know how I can make the changes made on the grid reflect on my database as well ?
I dont know how JQGrid passes data back to a servlet or php file. Is there any documentation for this ? I want to create my own servlet or java class specific to my application so that I can communicate with the grid.

Can anyone tell me how and what to specify in the url ? Is url the same as editurl ?

Thanks