FreezePanes Property
Set this property to True to create panes in the active worksheet. The panes are created above and to the left of the active cell. For example, setting this property to True while cell D5 is the active cell results in a horizontal pane between rows 4 and 5 and a vertical pane between columns C and D. Set this property to False to remove all panes from a worksheet. Read/write Boolean.
expression.FreezePanes
expression Required. An expression that returns a Window object.
Example
This example creates panes in the active worksheet.
Spreadsheet1.ActiveWindow.FreezePanes = True