First of all make sure that all the required items are already installed on your machine. You can view the requirements here, https://realmpksharepoint.wordpress.com/2014/07/10/install-sharepoint-online-management-shell-on-client-side/. The Microsoft.Online.Administration.Automation.PSModule dll is required to execute the

Connect-MsolService

command and get the return values in the form of type, Microsoft.Online.Administration.User from within the .net C# code. Well, it’s supposed to be a simple job of adding a reference of this dll to your project. The problem is to identify the location of this dll.

Initially, I did some googling to download the dll. However, I couldn’t find any trusted source (Microsoft) from where I can download this dll. Then, I realized that this dll should have been downloaded with the installation of Windows Azure Active Directory Module. Hence, I navigated to that location I found the dll at the following location

C:\Windows\System32\WindowsPowerShell\v1.0\Modules\MSOnline

Unfortunately, the job’s not done yet. A strange thing started happening here. Though, I can view this dll in my Explorer. The folder, MSOnline was inaccessible from the Visual Studio Add Reference window!

Still, I am not aware of this weird behavior. What I did to resolve this issue is, I copied the entire MSOnline folder to the bin directory of the project and from there I was able to add the dll’s reference to the project.