Have a look at the following Oracle article for the basics on connecting to the database from .NET
It shows how to connect to the database and retrieve records using SELECT statements. To perform inserts and updates you just need to change de command text with the appropriate SQL command, and execute it as non reader (i.e. replacing cmd.ExecuteReader with cmd.ExecuteNonReader).
<a href=”http://www.oracle.com/technology/pub/articles/cook-vs08.html”>Build a .NET Application on the Oracle Database with Visual Studio 2005 or 2008</a>