If it\'s not which I almost sure in, then what\'s the role of mscorlib.dll and where CLR is situated?
CLR
is not in mscorlib.dll but in MSCorEE.dll. I think that is what you were looking for. This is the main DLL loaded when an .NET exe assembly gets loaded.
See this question which probably answers you question.
I believe this question covers most of what you're asking:
mscorlib.dll & System.dll
The actual CLR code is contained in a file whose name has changed with different versions of the CLR. For versions 1.0, 1.1, and 2.0, the CLR code is in a file called MSCorWks.dll, and for version 4.0, the CLR code is in a file called Clr.dll.
mscorlib.dll is holding some fundamental classes of .net such as system.
use reflector to what classes and namespaces mscorlib.dll is carrying.
also your could find information on CLR here : http://msdn.microsoft.com/en-us/library/8bs2ecf4.aspx