There is no need for explaining about PhoneGap, cox every Mobile app developer knows how Great is PhoneGap.

 If you don't have any Idea about PhoneGap, I'll keep it simple.
There are 7 Major Mobile Platforms
     Each of these platform has different way of coding, you cannot use one code in another. This is where PhoneGap makes a Difference you code only once, use the same code (HTML5+CSS+js) in all the platforms. PhoneGap was recently acquired Adobe. PhoneGap has promised to remain not just free but Open Source forever.
"It will always remain free and open source under the Apache License, Version 2.0."

  There are two methods to add PhoneGap library files into your Project,
1. Easy
2. Complex

lets See the Easy Way..
 (This Method is Applicable only for Eclipse 3.6 & Higher Version, Eclipse Galileo(3.5) is not supported)

  Open Eclipse ---> Help ----> Install New Software ---> Add

In Field "Name" Enter anything, but "PhoneGap Plugin" is recommended.
"Location" Enter
 [(as on 09:45AM 16/Apr/2012 IST) Next Version is coming soon, comeback for the Updated Location.]

If you Get any Error try without SSL connection
This should Work

Old Version (Not Recommended)

 Click ok---> Next--->Next--->Accept the License --> Finish--> Ignore the Warning --> Restart

You will Find This Icon in your "Perspective "

How To Use PhoneGap Plugin in Eclipse.?

  Click on the PhoneGap Icon, you will get the below window, Do Not choose the Default Option,
 I suggest you to Go with the Option in the Red-Circle for the First time,

You are Done..!
Forget "" which is under "src" Folder. Do not do anything to it.
 Now Start Coding in "index.html" Do not Rename this HTML  or the Default Path...
You can Add *.js, *.css, images.
Make sure that all your Contents are within "www" folder.
Happy Coding  :)

You Might Get an Error in Manifest.xml if  your "SDK target" is below "3.0"
Open Android.Manifest.xml
find these lines


 Delete ==>    android:xlargeScreens="true"

Lets See the Complex

    I hate Spam the Complex Method is Already Explained Here