Updating Combobox Bound To Datagrid

I have a combobox in datagrid and i want to update data in combobox as current cell changed in datagrid so i want ti fill data in combobox as per the previous column of clicked cell

I am eager to know how did you bound the combobox to the datagrid,
I found the documentation on this site difficult to understand.
Please reply soon :)

I created a class called datagridcombobox and added it to tablestyle of datagrid and that to in 4 fields in datagrid and filled the combobox with different data from different table but the problem comes here it fills all data but i want paticluar data as per the previous cell of clicked cell in a current row.
So please reply me if you can help me on this topic

thanks.(Dewang)