Bose,
I'm not sure I fully understand your question but it sounds like you are trying to add text to a bookmark with the Word Insert Field.vi, but the text is instead inserted at the end of the document. The Word Insert Field.vi only inserts the text at the end of the document if no bookmark is specified in the bookmark input of the VI. Make sure that you are specifying the correct bookmark at this input in order to add text there.
If I've misunderstood your question, feel free to ask again, but try to clearly explain what you are trying to do, how you've tried to do it so far, and how those attempts have failed.
Regards,
E. Sulzer
Applications Engineer
National Instruments