Hi Channa, is it a field or a button you want to add? For a custom field you can refer to Anils answer, but if you want to add a button, that is another story.
As of SRM 7.02 you can use the SPRO activity "Define Toolbar Button" to add buttons. In previous releases you will need to edit the relevant BSP views (in this case order/detail_view.inc for example) and add your buttons in the BSP coding.
regards
Zoltan