I have completed the gui(asp.net) part of my shopping cart..website need to connect with database for updating news and images of product for shopping and to hold transaction details...i am really new to this type of site...can anyone guide me to judge my choice and how to connect .mdf file with asp using vb.net to insert and query data

Connection strings for SQL Server:

SQL Server 2008 Connection String Samples - ConnectionStrings.com

To answer your question:

Yes, Using Microsoft SQL Server is a good idea. Well, assuming your company is using SQL Server. SQL Server has many pwrfl capabilities for handling ... gods, pretty much all kinds of data. You can even stuff XML data into table columns, which could be handy-dandy when working with news updates.

But then again, as someone who swears by Microsoft Technology of pretty much any variety, I may be a slightly biased resource to consult. If you asked my identical twin sister (also a web developer) she'd probably say "SCREW SQL SERVER, MYSQL IS FREEEEEEEEE" or something like that... that's the reason my web development company didn't work out... database and platform wars. but I digress.

The thing I like about Microsoft SQL Server, especially since you're using ASP.NET, is that it provides such an enormous platform that does a lot of the legwork for you.