I am trying to buy my photobook on iphoto but its saying its default text what does that mean?
It means that you did not write text into all text fields. At least one of the textfields is still empty (and has the default "Lorem ipsum" text written into it). Apple writes some "default text" into the text fields and you are expected to replace that text with your own text. It could be some title or caption. Or a text field, that has slipped behind a photos box.
Create a preview of your book and check for missing text.
See: iPhoto, Aperture: Previewing an order in iPhoto or Aperture