You are using this example. On the same site you can find an example how to get the number of pages of a tiff. You can combine the two examples to extract all pages by looping from 0
to num_of_pages - 1
with a simple for loop and build the appropriate two strings and with these two strings the argument array for TiffCP.Program.Main
for every index.
First page -> string[] arguments = {@"Sample Data\multipage.tif,0", "SplitTiffImage_Page1.tif"
Second page -> string[] arguments = {@"Sample Data\multipage.tif,1", "SplitTiffImage_Page2.tif"
and so on...