How to put all rows in edit mode

I have 2 gridviews.  One has the Master table, the other has the details table bound to it.

I can click a select button from the master and that shows all the records in the details grid.  What I need to do is click a edit button and have all the rows go into edit mode so that they can tab around to edit fields.  I also would like only certain columns to be editable.  Any Ideas on how to get them all in edit mode is greatly appreciated.

thanks