GRidview Textboxes

Question

hi,

i am using 4 text boxes and a grid view in one of my application.I need to add the textbox values to the gridview,clear the textbox values and then enter the values into textboxes and click on button they should again go to gridview and the previously saved in the gridview should also be their in the gridview

Every Time i Enter values the 3rd and the 4th textbox values should add to the previous entered values and should be displayed on the gridivew

Please Helpme out