Open IIS manager , right click on the application pool in the left pane , click create new application pool , give ID to the application pool , check use default settings for new application pool , check ok . The application pool is created . Now Expand the websites option , right click on the website to which you need to give dedicated application pool which you have created , Click properties , home directory tab , in the application pool drop down box select the application pool , click ok .

Regards,

Paul .