If you bind a DataGridView to a collection/ data source then the data in the data source will be updated when you change it within the DataGridView.
Your question is very vauge and as part of using DaniWeb you have to show what you've done so. This is to show you have attempted it yourself first and so that people can try to see how you're doing it.
Here are a few more links that may me of help. One of them is about the DataGridView object and describes how it can be used...
Just for clarification to respondants, GridView and DataGridView are not synonymous. OP, can you specify whether you're using WinForms, WPF, or ASP.NET such that helpers don't need to make assumptions about your terminology?