Data Filling in datagridView comboBoxColumn

Sir , I am doing a ADO.NET Program.

I have two forms; frmProduct and frmPurchasedetails

frmProduct :-




please take a look to the columns Product Name and Purchase Rate . These columns too in frmPurchaseDetails

here is the frmPurchasedetails;



You can see the columns Product Name and Purchase Rate. This columns stands for the same data of frmProduct.

So I want this columns to be filled.

How i can fille this two columns in the frm_Load Event?

 please reply