You will need to show some code for what you're trying to do.
But with any SQL systems, each INSERT statement should include a list of columns that are being inserted. As long as the new column is in the list, and is provided with a value, there's no reason it would not be inserted.
As a general hint, and unrelated to your question, try to avoid referring to a "null value". A column IS null. It doesn't have a null value. Being null means that is has no value.
If the columns are in your INSERT statement and not being inserted, you'll need to give us some SQL code to look at (i.e. the table definition, and the INSERT statement)