In IIS7 and higher one of crucial points in web site configuration is Application Pool. A lot of developers who are new to IIS7 and higher IIS management console, ask a very basic question, How do I find Application Pool for the site?. Here is answer to this question.
Bring up IIS Managager console from Administrative tools.
Select the web site or web application, for which you find to configure Application Pool, in left hand side pane.
In the right hand side pane, click on Basic Settings link.
It will bring up following view, where you can see your application pool for your web application.
Click on Select button if you want to see all the pools that are available to you. This is where you can change Application Pool for your application.