i am hanged in data grid

Question

my problems is that suppose i have a data base having fields lets say name and age. now on interface i have two textboxes, two buttons with captions add and save and a data grid. user is allowed to enter name and age in two textboxes and when user clicks on add button name and age in text boxes should move to datagrid and filling the textboxes blank so that user can insert other name and age in textboxes.now user again enters name and age in text boxes and clicks on add button so these values become the second line of data grid . Finally when user clicks on save button data in the data grid should be saved to database. here primary key constraint must be checked when data moves from text boxes to the data grid. please help me. i am a student.