KawaGeo
After installing the toolkit, do you not see the templates available under your 'New Project' dialog?
If this is happening, it's possible that the DarkGDKApplication.zip file has been installed in the incorrect Templates folder. If you look at your Documents/Visual Studio 2008/Templates folder, there should be a Visual C# folder which contains the ZIP file. If it's not there, this will be the reason why you cannot see your templates.
Can you examine your HD and tell me what you see in the Visual Studio 2008/Templates folder?
Paul.
[EDIT] To clarify, your Templates will be located under the C:/Users/[Your User Profile]/Documents/Visual Studio 2008/Templates folder for Windows Vista and Windows 7.
For XP, it's under C:/Documents and Settings/[Your user Profile]/My Documents/Visual Studio 2008/Templates