I'm not sure why you need to find the DataGridCell using VisualTreeManager nor do I know currently how you would properly start editing . You may get away with simply setting the cell's visual state to editing.
I have a xaml file that contains a silverlight DataGrid. As you know, that in a silverlight Datagrid, whenever that user starts editing a line (a row) the beginEdit is called automatically, and then when he finishes editing EndEdit is called... This works fine with DataGridTextColumn and DataGridCheckBoxColumns.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.