GIS Application in .NET

Question

Hi all,
I am not sure this is proper place to post this topic but if any one can help me then it will be very helpful for me.
 I am developing GIS application using ASP.NET 3.5.
The database we are using is Postgresql and NHibernate to store data.
I can store simple data. But I am unable to store data for Geometric field like Box, Polygon etc. using .NET. I have searched on net but not getting good sample code/tutorials.
Can anyone please help and guide me ?
Thanks and Regards
Prasad