Content can be displayed inline or using a module:

Using Inline content
Guests will see the content within these tags {guest}{/guest}.

Example: {guest}content to display{/guest}
Will show for guests: content to display

and Registered users will see the content within these tags {registered}{/registered}.

Example: {registered}content to display{/registered}
Will show for registered users: content to display

Using Modules
To include content for Guests, use will see this:
{displayguest modulename}

To include content for Registered users, use this:
{displayreg modulename}

Where "modulename" is the name of a custom module.