Not sure what you mean by "... without the need to hit any buttons." You need to take some sort of action at the UI for the data to be saved unless you have the application do some sort of auto-save every few minutes. This question is similar to yours and may have some information that you can apply
http://stackoverflow.com/questions/520051/c-issue-how-do-i-save-changes-made-in-a-datagridview-back-to-the-datatable-used. If you want to use the 'auto' style save then you simply need a routine in your code that does the same save process as your button_onclick method and you are good to go. I am not a developer so this is all theory and you will have to locate proper coding procedures and methods to make sure you follow best practise.