Don't you have Publisher, Home Publishing, or PictureIt! Publishing on your
computer? These programs are made especially for doing projects like this?
Word really isn't the best tool to use for cards. (But it can be done, as
I'm sure someone will tell you.)
It does depend on what size greeting card and what size paper (i.e. how many
folds).
This also depends on Word version but you could just type it big as two
pages and then print 2 (portrait) pages per one (landscape) sheet in the
print dialog.