How to set application pool for Html Agility Pack

How to set application pool to a website using htmlagilitypack? I'm currently using app pool - local system, when I run my code I get an error that says "Unable to connect to the remote server"

                HtmlAgilityPack.HtmlDocument doc = hw.Load(url);
            HtmlNodeCollection nodes = doc.DocumentNode.SelectNodes("//a[@class='metatag-topi metatag-keywords']");
            HtmlNodeCollection nodes2 = doc.DocumentNode.SelectNodes("//div[@class='pagination']/a[@href]");
            HtmlNodeCollection phone = doc.DocumentNode.SelectNodes("//p[@class='phone fRight ml10']");

To use the UI

Open IIS Manager. For information about opening IIS Manager, see Open IIS Manager (IIS 7).
In the Connections pane, expand the server node and click Application Pools.
On the Application Pools page, select the application pool that contains the application that you want to change.
In the Actions pane, click View Applications.
Select the application whose application pool you want to change and then click Change Application Pool in the Actions pane.
In the Select Application Pool dialog box, select an application pool from the Application pool list and then click OK.

Command Line

To change the application pool in which an application runs, use the following syntax:.

appcmd set app /app.name: string /applicationPool: string The variable app.namestring is the name of the application that you want to change, and the variable applicationPoolstring is the name of the application pool to which you want to add the application. For example, in a site named contoso, to add an application named deals to an application pool named Marketing, type the following at the command prompt, and then press ENTER: appcmd set app /app.name: contoso/deals /applicationPool: Marketing For more information about Appcmd.exe, see Appcmd.exe (IIS 7).

Configuration The procedure in this topic affects the following configuration elements: element under For more information about IIS 7 configuration, see IIS 7.0: IIS Settings Schema on MSDN.

WMI

Use the following WMI classes, methods, or properties to perform this procedure: Application.ApplicationPool property

For more information about WMI and IIS, see Windows Management Instrumentation (WMI) in IIS 7. For more information about the classes, methods, or properties associated with this procedure, see the IIS WMI Provider Reference on the MSDN site.