<p>I am really stuck with this Parser Error Message telling me "<code>Could not load the assembly 'App_Web_amlohswi'. Make sure that it is compiled before accessing the page.</code>"  I have been looking around for a few hours checking different posts here and googling information.  I have found out that I need to set up a new Application Pool that runs <code>.NET 2.x</code>.  </p>

<p>(On a side note, my app is being developed in <code>.NET 3.5</code>, is there a way to set it up to use <code>3.5</code> instead of <code>2.x</code>?)</p>

<p>Can someone provide me with a good explaination on how to set this up properly and (optionally) why is it necessary?</p>

<p>I am more used to developing in PHP so I am used to edit src >> upload >> success!</p>

<p>Thanks!</p>

ASP.NET 3.5 sites run in 2.0 app pools as long as that version of .NET is installed on the system.
You may have to set up web.config properly. Visual Studio should do this for you when you create a new project.
You should also make sure you don't combine 1.1 and 2.0 applications in the same app pool. Try putting it in a separate app pool and see that helps.