You first need to add the ZedGraphControl
to your toolbox. The instructions on the Zedgraph CodeProject page works for Visual Studio 2012 as well:
ZedGraph is accessible as a control from the control toolbox in Visual Studio .NET. To access ZedGraph, first launch Visual Studio .NET, and create a new Windows Application (Forms) project. Open the form design so that it appears in the current window. View the toolbox using the View/Toolbox menu command. Right-click inside the "General" or "Components" sub-pane of the tool box, and select the "Choose Items..." option. Click "Browse...", and navigate to the ZedGraph.dll file. Once this file is added, you should see a ZedGraphControl
option in the toolbox.
If you want to use an alternative charting library, please be aware that .NET 4 and later contains the .NET Charting library for Windows Forms out-of-the-box, see here.