Edit doc file through C #

I have a program that generates barcodes, inserts them into a .txt file and prints this file. What I want is for these bar codes to be inserted into a doc file with a label paper template (in this case they are Pimaco labels size 6287) so that, at the time of printing, the codes come out right on the label. Otherwise I'll have to use a plain label sheet and then cut each one.