/nfs/h3ulcb *(rw,no_subtree_check,sync,no_root_squash,no_all_squash)

After entering the 
sudo vi /etc/exports

page, I enter the page that starts with # /etc/exports: the access control list for filesystems which may be exported
# to NFS clients. See exports(5).

and add
/nfs/h3ulcb	*(rw,no_subtree_check,sync,no_root_squash,no_all_squash)
/nfs/m3ulcb	*(rw,no_subtree_check,sync,no_root_squash,no_all_squash)

How do I go about saving this after these lines have been added.
Is there a specific thing that must be typed in to save and exit?