Adding records to two tables with a one-to-many relationship

I have a task of creating a form which adds a new record to a main table, while allowing the user to add multiple records to a second table, analogous to transactions against the new record in the main table.
The second table has a foreign key relationship to the main table.

Is this just a matter of allowing the user to click a "GO" button and including C# code which will add the new window values to both tables? What would be the best way to get the code behind the "GO" button to save field values to both tables?

The resulting web-based form(using SQL Server and C#) would be providing a record maintenance interface which duplicates a task which is already done via a longstanding paper form.