How to Populate a comboBox Column with another ComboBox column in a DataGridView using C#

I have a datagridview comboBox column with 2 items in it,"Cars" & "Bikes". I also have another datagridview combo Box column in the same datagridview.When i select "Cars" in the 1st comboBox, i should display the list of cars in the 2nd comboBox & when i select "Bikes" in the 1st comboBox Column, i should populate the 2nd comboBox column with the bikes list.I am writing the code using C#.NET, can any one help me with this !!!!!

Can any one provide me with the code ?? i am new to C#

thanks, in advance....