How to make silverlight datagrid editable?

I created a simple collection of Person with name, 开发者_运维技巧age and sex where all three fields have getters and setters. I bound the collection to the data grid using the itemssource. I can see the data been showed up in the data grid but it does not allow me to edit any of the rows. What do I make so that it becomes editable?

Thanks.

Something like this should do the trick...

<sdk:DataGrid ItemsSource="{Binding Person}"
                                  SelectedItem="{Binding SelectedPerson, Mode=TwoWay}"
                                  IsReadOnly="False">