Can anyone suggest a fix? Thanks in advance for your help.
<apex:page showHeader="false">
<apex:pageBlock title="User Status">
<apex:pageBlockSection columns="1">
{! $User.FirstName } {! $User.LastName } ({! $User.Username })
</apex:pageBlockSection>
</apex:pageBlock>
</apex:page>

Challenge not yet complete... here's what's wrong: 
The Visualforce page did not fit the criteria. The first name of the logged in user was not output using dynamic global variables.