To change the text that appears in the sample line first select the line(s) in the report that you want to appear by clicking and dragging in the leftmost part of the window. This will show the lines in reverse video.
Now click the little icon next to the trap line number, and before the A N B trap icons, the one with the red and black lines on a page. The tool tip reads "Replace Sample Text".
We all started out the same way Steve: as absolute beginners. Welcome aboard.
For tweaking your template you might need to use the arrow icons to shift your fields left or right, and don't forget that double clicking on a painted field will open up the properties dialog for that field. You might find that adjusting the template width here is easier than playing with painting the fields.
And don't forget to use the Verify feature to double check that you haven't accidentally cropped a field too short on one side or the other.