Hello,
Can you be more precise where you saw the copy / paste instruction in the Blue Kenue manual.
If you already have bathymetry and coastline, it would be better if you can either open the files (if you can fit these in the Blue Kenue native file formats) or if you import the files (from GIS or global database type formats).
Note that there is a tutorial on mesh generation with Blue Kenue that might help you further:
Blue Kenue Tutorial, or form the developer of Blue Kenue, Martin Serrer:
Blue Kenue @ NRC-CHC.
Hope this helps,
Sébastien.