for (byte i =  0 ; i <=  7 ; i++)
{
myGridView.Columns.Add(new GridViewColumn());
template = new DataTemplate(typeof(string));
FrameworkElementFactory factoryTXT = new FrameworkElementFactory(typeof(TextBlock));
if (i ==  0 )
   {
      factoryTXT.SetValue(TextBlock.TextAlignmentProperty, TextAlignment.Left);
   }
else
   {
       factoryTXT.SetValue(TextBlock.TextAlignmentProperty, TextAlignment.Right);
   }                
factoryTXT.SetValue(TextBlock.MinWidthProperty,  75 . 0 );
bind = new Binding("[" + i + "]") { Converter = new myConverter(), ConverterParameter = _strFormat1 };
factoryTXT.SetBinding(TextBlock.TextProperty, bind);                
template.VisualTree = factoryTXT;
myGridView.Columns[i].CellTemplate = template;
}
WrapPanel wrp = new WrapPanel() { Width =  75  };
wrp.Children.Add(new TextBlock() { TextWrapping = TextWrapping.Wrap, Text = "сальдо на начало месяца", TextAlignment = TextAlignment.Center });
HeaderedContentControl header = new HeaderedContentControl() { Content = wrp };
myGridView.Columns[ 0 ].Header = "месяц";
myGridView.Columns[ 1 ].Header = header;

myGridView.Columns[ 1 ].Header = new HeaderedContentControl() { Content = new TextBlock() { Text = "текущий план пост-я",
TextWrapping = TextWrapping.Wrap, TextAlignment = TextAlignment.Center, Width =  75  } };

GridView.ColumnHeaderTemplate = ?