I have to develop e-commerence web portal, i am confused whether to use asp.net web form, dotnetnuke or asp.net mvc ? I dont have experience with dornetnuke so is it good to develop such portal? Thanks .
Since you are new to StackOverFlow, I'll answer your question. However, please do not ask opinion based question anymore.
DotNetNuke is not a technology instead it is a CMS which is written in ASP.Net Web Form.
On the other hand, Orchard and Umbraco are written in ASP.Net MVC.
If you are new to ASP.Net shopping cart, you might want to read Beginning ASP.NET E-Commerce in C#: From Novice to Professional (Expert's Voice in .NET) in which you will be creating a small shopping cart site using PayPal.
If you are primarily look for an open source shopping cart, nopCommerce (written in MVC) is one of the best. But it'll take few days to few weeks to understand the concept depending on your experience.