Page setup for gridview

Question

Hi,
  I am using Next, Previous,First and Last buttons for the gridview control in asp.net. i am displaying around 25 rows of data per page in the gridview. after clicking next button it should display the next 25 rows of data i.e from 26 to 50th row it should show. after clicking previous button it should show last 25 data in gridview. first means it should go to the first page and last means it should go to the last page of gridview. how to do this using asp.net. please can anybody help me regarding this.