Cerating Firefox Extension

Keen about Developing/building firefox extensions?.Well ! It's easy to develop extensions for the firefox.You need to have understanding of XUL and Javascript.
Basically, this POST will introduce you how to create your first firefox extension.

Extensions are packaged and distributed in ZIP files, with the XPI (pronounced “zippy”) file extension.
The basic structure of a XPI package is as follows.

emptySidebar.xpi:
    /install.rdf         
    /install.js
    /chrome
       |- emptySidebar.jar

Folder Structure is as follows.
emptySideBar
           /install.rdf         
    /install.js
    /chrome
        |- content
        |    |-login.xul
        |    |-helloworldOverlay.js
        |    |-content.rdf
        |- skin
        |- locale

A folder and two files. install.js was all you used to need for the installation, but now that the extension manager has changed (since Firefox 0.9), the install.rdf is used instead.

Chrome foleder contains another archived file, emptyBar.jar.which has three folder.
content - contains all XUL and related ,JavaScript files and content.rdf file.
skin - contains all layout files like CSS and images used in the XUL files.
locale - contains language specific information.

Once this is done, you are ready to create launcher for your extension.
Step1
go to emptySideBar/chrome/ directory.

zip -r emptySideBar.jar content/ skin/ /locale
cd ..
zip emptySideBar.xpi install.* chrome/captain.jar


Once xpi is created upload it to you server and call it from the firefox mozila.

For more information click here