Can't get Microsoft.Office.Interop reference to work

I have a C# winforms app and I am simply trying to open an Excel sheet. When I try to add a reference to Microsoft.Office.Interop, the "Office" part is red and says "Can't resolve symbol 'Office'".

When I attempt to build, the error is:

The type or namespace name 'Office' does not exist in the namespace 'Microsoft' 
    (are you missing an assembly reference?)

I have Office 2012 installed, and I think I have the Primary Interop Assemblies installed... but I'm not positive.

I know that this should be so easy, but I've been looking around for an answer to this for almost an hour and just can't figure it out. Thanks in advance!

Solution

You need to add the library assembly reference to your project. They are referred to as "Primary Interop Assemblies".

(Assuming Visual Studio 2010)

Procedure

open the solution explorer window
expand your project folder accordion.
right click on the references element
select "add reference" from the dropdown
select the .NET tab and look for the object library called Microsoft.Office.Interop.Excel.
click ok

The object library should now appear in your references.