90% of what you do in C# (or any OO language for that matter) is in functions.

I am not sure exactly what you are asking though - I know you are new to C#. You ask if you can put some repetative...

when do you call CalcColumn()?
You havent quite grasped the concept which is where you are going wrong but thats why we are here :)
Are you using a strong typed dataset to get your data? You dont...

database1Dataset.Columns.Add(Column1);
that line is incorrect
Cannot add a column to a dataset... need
database1dataset.Tables["sales"].Columns.Add(Column1);
if sales was the table name

you create an unbound column in the sales and use the Expression property whose value is quantity*price (assuming those are the two column names). Only create bound columns if you want data saved in...

I am slightly lost but i think i know what you mean.
In design view in all VS (2002, 2003 and 2005) you can click the events icon in the properties box (normally you have it in properties view to...