You do need to setup the '/etc/exports', '/etc/hosts', '/etc/hosts.allow' and '/etc/hosts.deny' files. Once you have the proper structure then as root 'exportfs -ra' will update the table.
excerpt from 'man exports';
EXPORTS(5) Linux File Formats Manual EXPORTS(5)
exports - NFS file systems being exported (for Kernel based NFS)
The file /etc/exports serves as the access control list for file sys-
tems which may be exported to NFS clients. It is used by exportfs(8)
to give information to mountd(8) and to the kernel based NFS file
server daemon nfsd(8).
The file format is similar to the SunOS exports file. Each line con-
tains an export point and a whitespace-separated list of clients
allowed to mount the file system at that point. Each listed client may
be immediately followed by a parenthesized, comma-separated list of
export options for that client. No whitespace is permitted between a
client and its option list.
excerpt from 'man exportfs';
exportfs - maintain list of NFS exported file systems
/usr/sbin/exportfs [-avi] [-o options,..] [client:/path ..]
/usr/sbin/exportfs -r [-v]
/usr/sbin/exportfs [-av] -u [client:/path ..]
The exportfs command is used to maintain the current table of exported
file systems for NFS. This list is kept in a separate file named
/var/lib/nfs/xtab which is read by mountd when a remote host requests
access to mount a file tree, and parts of the list which are active are
kept in the kernel's export table.
You should 'man exports' and 'man exportfs' to get a understanding of the commands and necessary structure.