C# and VB.NET classes uses in the App_Code folder

Create two folders under App_Code folder named CScd and VBcd. Put all .cs class file inside CScd folder and .vb class file inside VBcd folder.

Add a web.config file to your web site and add the following to it:

add compilation tag in web.config file and add codeSubDirectories as it subtag in that add these two line
< directoryname="CScd">< /add >
< directoryname="VBcd">< /add >