items from a comboBox to a dataGridView ¿?

Hi there guys, how can i pass the items from a comboBox to a dataGridView ?, when i click on a button (btnAdd) the selected item from a comboBox populate the dataGridView, so i can add some items from the comboBox to a dataGridView.

I have the comboBox filled with a column (attribute) from a table in the DataBase. I wat to load all the tuple(from that table) of the selected item (attribute) in the comboBox as a row of the dataGridView.

Thanks in advance for your help, i will apreciate too much