Help!!!!

I am trying to make the labels that will attach to the belly band on my invites. I have made them using the labels tab in the envelopes and mailings section in Word. My question is how can i add a watermark to this. I want to makethat last initial a background watermark design. I know How to do watermarks but it won't appear in the background behind each label only in the center of the actual page. Does anyone know how I can do this? you can see what i have so far in my album.

TIA