asp.net 2010 files

Question

I have a C# 2010 web form application that I have a question about files in the bin directory. I have created a setup and deployment project and installed the application on a test iis server. Can you tell me what format the application1.dll and application2.dll format files are in? Basically if I want to decompile those dlls, would those applications be in an msil format, a C# 2010 .net format or what format would those files be in?

Next step is I want to see the *.cs code from those two dll files. Thus if the code is in an MSIL format, what can I do to get the code in a *.cs readable format?