1. Open IIS Manager and click on Default Web Site.
2. In the Actions pane, click on Basic Settings... and then click on the Select... button, highlighted in the next figure:

3. The application pool window will pop up. Click on the Application pool: drop-down menu, select 2and3.5AppPool under Application Pools, and click on OK to finish this step.

4. Now, in the site properties, you will see the v2.0 application pool associated with the Default Web Site:

5. Next, right-click on Default Web Site, click on Explore, and you will get the wwwroot directory, where you have to upload the v3.5 .NET web files:

6. We have thus uploaded the v3.5 files to the wwwroot directory.