Local Database editing in C#

Question

Hey, I am working on a project for my uncle where I have to keep a record of his stuff in his store. I have created a local database in C#. The problem is that I want to give the user the ability to add a column when he wants by just clicking a button. Can anyone please tell me what could be the lines of code for just adding a column?? I can do the rest i-e button click check and all other stuff. I need only the code lines (Query) to add a column. Thanks