[NTG-context] how to put page X of N in header or top space?

Hi, I am slowly learning ConTeXt. I am generating tables and spreadsheets, and transforming them into ConTeXt, finally got it working after a lot of mysterious errors about missing } as macro arguments. I have read this page carefully: http://wiki.contextgarden.net/Layout How can I alter the page number? Is it in the header, or is it in the topspace? I want this to be at the top of each page of my spreadsheet: My Spreadsheet (centered) Page 1 of 3 (right justified) And on even pages, the other way around: Page 2 of 3 (left justified) My Spreadsheet (centered) What is the right way to do this? Is there an override and a blob of code I need to put into one of the boxes in the Layout? David