When we want to see the disassembled code we will go for the ILDASM tool and give the mapped path of the dll and see the disassembled code in the tool
Check this out.
From the Microsoft site:-
This tutorial offers an introduction to the MSIL Disassembler (Ildasm.exe) that is included with the .NET Framework SDK. The Ildasm.exe parses any .NET Framework .exe or .dll assembly, and shows the information in human-readable format. Ildasm.exe shows more than just the Microsoft intermediate language (MSIL) code — it also displays namespaces and types, including their interfaces. You can use Ildasm.exe to examine native .NET Framework assemblies, such as Mscorlib.dll, as well as .NET Framework assemblies provided by others or created yourself. Most .NET Framework developers will find Ildasm.exe indispensable.