grid view binding in asp.net

I have a page in which a have a grid view in which values are coming from database and it have edit and delate option .
but for adding i have text boxes below grid view , not in grid view.
please tell me how to add values of textbox to gridview or tell me that if i do it another way that i use textbox for inserting new values in of grid view how can i make them show if there is no other values in grid view.