Assumptions: You're connected to a Local Area Network and your NIC has already been configured with the proper IP and subnet. Of course, basic mouse skills will help. (Addendum to assumptions: You just want a simple share, meaning you just want everybody in the LAN to view, copy, and edit the shared resource.)
Install the samba and smbfs packages with the Synaptic Package Manager. Open Synaptic (System -> Administration -> Synaptic Package Manager) and search for the samba and smbfs packages. Right click on it and then choose install. Click apply. Close Synaptic when finished.
Create a folder in your home directory. Click Places -> Home. Ctrl+Shift+N to create a new folder and name it SharedFolder.
Change its permissions to 777 (or read-write-execute permission to User/Group/Others). Right click on the folder then Properties then click the Permissions tab then make sure all the read write execute check boxes have checks on it.
Now to share the folder... click System -> Administration -> Shared Folders. Click Add. At the Path selection, click the up and down arrows then choose others to browse your home folder.
Now as you see the SharedFolder folder that you just created, make sure you double click on it and not single click. Click Open. Put something on the Name field (like SharedFolder) then also put a check on the Allow Browsing Folder option. Click on General Windows sharing settings. Put anything on the Host Description field, then put your LAN's workgroup at the Domain / Workgroup field (in my case is MYGERONA). Click OK.
For the settings to take effect, you should do something at the terminal but for the sake of avoiding the terminal... just restart your PC. :)
That's it. Tried and tested it with two PCs and one laptop.. all fresh installed with Ubuntu Dapper.
I hope it works for you too. :)