calculating values of a row in a table

Am building a web site that deals with student registration and using asp.net
But am finding it difficult getting the right codes to both calculating the values
Of a column in my table, and how to connect an insert trigger to this so that the calculated values re added to the database and since am using an empty database I need codes that will only insert into the database and NOT display the content
of the dataset. I ll appreciate any help rendered