How to style a byline field in an article content type?
It would be helpful to see the markup that surrounds the newsbyline field. I'm guessing there's a div or some other element around field_newsbyline that's a block element by default. If you change the CSS for that element to display: inline that may solve the problem.

Alternatively, if the above code is in your node template, you could adjust the markup in the field template instead: 


Copying field.tpl.php from the base theme you're using or from Drupal core's /modules/field/theme/ into your theme
Rename it field--field-newsbyline.tpl.php (assuming field_newsbyline is the machine name of your field)
Edit that template to add &lt;?php print t('By'); ?&gt; in the appropriate spot.


By making the change in the field template, you should be able to get your code inside the wrapper div, rather than having it outside.