Dealing with gridview in asp.net

When I added 'edit' column to gridview,I got this problem:

The GridView 'RegisteredList' fired event RowEditing which wasn't handled.

How I will fix it? and Thank you very much..

From stackoverflow

• You need to handle the event RowEditing. In the markup:

  <asp:GridView id="RegisteredList" runat="Server" 
  OnRowEditing="RegisteredList_RowEditing"/>
  

  And in the code behind:

  protected void RegisteredList_RowEditing(object sender, GridViewEditEventArgs e)
  {
      //do stuff
  }