By default, there is no application for LAN file sharing installed in Ubuntu. Throughout this post, we are going to install one (named Samba) so as to be able to do the thing.
First, choose any folder you like to share, and right-click on it, then choose Sharing Options
Check Share this folder, then the system will ask you to install additional software (Samba). Just install it.
Finally, click on Create Share to share the folder; the folder’s icon will look like the following:
To access the shared folder through the other computers of the network, just open up Nautilus, in the left sidebar click on Browse Network then choose the name of the computer in which the folder is shared and you will see it.