OK, the idea of backlighting is for the light to come from behind the object.
In my opinion, the light may be behind and above or higher than the object. Either way it's coming from behind. Same thing with the sun being your backlight. Most of the time it will be behind and above the subject.
The reason I bring this up because I think some people may be voting the images (at least my image) down because the light is not in horizontal line behind the object.
Well to me behind and above is just as good for the challenge and the horizontal line behind.
Above, below, from the right side, from the left side - all are good as long as the light is from somewhere behind the object, or hilighting something behind the object.
and backlighting does NOT have to be from a directional light source. ie. light that is REFLECTED from behind the main image is also backlit.
I think some people are confused about this aspect of backlighting. A common technique in studio shots is to bounce the light source off of a reflector of some sort onto the back side of the main subject.
There are a few shots in this challenge that are a little confusing and some people might think they are not backlit.
I am pretty new to all of this and exprimented with the lighting, I had soft light at the back/side and stronger from underneath my setting, I have had a couple of comments about my lighting not being back lit but nothing horrid :) I do wish in retrospect I had taken the care to experiement further with my entry, I spent about 1 1/2 hours with the set up and taking of my entry, I like what I did but wish I had not left it until almost bed time to do it!! I am enjoying the challenges but I have so much to learn! I think it does not realy matter about the light source as long as the desired affect is achieved. Anyhow good luck - I'm on a 5.4844 at the moment so am pretty contented. It is doing much better than my travel guides pic which has a flaw in it I did not notice until it was pointed out to me :( good luck everyone :)