Vikash, in English, the pronoun "I" is always capitalized. Also the period (.) at the end of a sentence should not be preceeded by a space. Paying attention to the little illogical details of the language makes you look more professional.
Eclipse can be confusing since Eclipse is a Java program that contains and runs Java programs. However, the Eclipse classpath applies only to the Eclipse program itself, not to the applications that are being maintained in Eclipse.
The classpaths for those applications are contained the the ".classpath" file that is one of 2 files that define an Eclipse Java project - the other file is named ".project". The .classpath file is maintained as follows:
1. In the Navigator view, right-click the icon that defines the root of the project (has the project's name). Select the bottom-most item (Properties). This will display the Project Properties Dialog.
2. On the Project Properties dialog select Java Build Path. This will display a series of tabs.
3. Select the Libraries tab. This is where you define the POI jars to the project. At a minimum, it will have a JRE System Library already defined in it (otherwise even java.lang.Object will be show an error as an undefined type).
Where you keep the libraries is up to you. I often just make a "lib" directory in the project, but for Eclipse, the exact location isn't important except for one thing - if you keep the POI jars within the project, use the "Add JARS" button to define them to the project. Otherwise use the "Add External JARS" button. Make sure that ll the POI jars are displayed in this dialog, then click OK to finalize their definition.
That's all
you should need to be able to edit and
test your POI app in Eclipse. I'll leave the details of setting up the app to run outside of Eclipse for a later time.