Setting a context menu for Datagrid field.

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I have a 2 columns, 5 rows datagrid with 1st column ReadOnly, and 2nd Column
Editable, (e.g ResourceFiles, Path)
I am trying to make a context menu to open file dialog for path searching.
But I am not able to correctly locate the selected row from the datagrid.

Example:
ResourceFiles Path
res.txt XXXXXXXXXXXXXXXXXXXX

My codes is as follows.

private void Context_Browse_Click(object sender, EventArgs e)

{

this.OpenDialogFile.Title = this.DG_Resource.SelectedRows.????

}

What I want is to get the Dialog Title to be the value from [ResourceFiles]
in the Datagrid's Column 1. Please advise i should i do it?

Thanks in advance.