First,type following in terminal to install NFS:

sudo apt-get install nfs-common
sudo apt-get install nfs-kernel-server

Edit /etc/exports by :

sudo gedit /etc/exports

Using this command to configure the folder you want to share:

/home/armnfs    192.168.1.6(rw)

this will share /home/armnfs folder,and only 192.168.1.6 can access to this folder.”(rw)” means write and ready permission.
Now,start NFS:

/etc/init.d/nfs-kernel-server start

In the computer(192.168.1.6),use this to mount the shared folder:

mount 192.168.1.5:/home/armnfs  /mnt/arm