may be it's a dumb reply, but is it the (a) preview pane you are talking about or (b) the actual app deployed on the web server and viewed through browser.
If it (a) then don't worry about it it will be ok when you actually deploy it.
if it's (b) then you must have felt like after reading the above two line.
In that case I don't have any concrete suggestions coz this never happened to me before. However you could check if your project path includes the jsf implementation jars and that the 'UserBean' has proper entry in <managed-bean> section.
I guess you just run the first example of RoseIndia.
Make sure you write a java file with name UserBean and a property with getter /setter methods named userName in that. Define this java file in faces-config with <managed-bean> and <managed-property> attributes.
If you go through further in the same site, they might have provided all these bean and config info.
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