Hello.
I am fairly new to Photoshop so my question may sound a bit ridiculous but here goes.  Recently I made a 3d digital image from which I wanted to add a fire to.  I saw an advertisement for a Photoshop brush that said it could be used to paint fire onto images so I bought it, installed it, and used it.  But when I used it all it did was make patterns on my screen of fire shapes that were a flat color; the color I currently had selected.  What I had hoped was that the brush would not only paint the shape of a flame but the acutal photorealistic colors of the flame like I saw in the advertisement; but it did not.  I am not closer now to adding that piece of fire to my scene now.

I had a similar repeat of this event when I purchased a set of Photoshop brushes advertised to create many mystical special effects.  The advertisement looked very impressive of glittering speckles and magical swirls of fantasic colors.  Unfortunately, I bought this set of brushes and ran into the same situation; I could paint patterns or shapes of the mystical things in the advertisement but the cool neon colors, radiant effects of light, etc. were not coming out like the advertisment that came with the brushes. 

Am I doing something wrong here?  Are there such things as brushes that all you do is paint with them and the colors and effects that are on the advertisments with them also automatically appear?  Or am I supposed to create on my own all the lighting, neons, speckles, etc and then use the brushes to apply my creations?  If so then what books or places of information can I access that will show me how to make such effects for post reneder work in 3d digital art?

Some of the products I am not able to make work due to my limited Photoshop knowledge are:

50 Photoshop Brushes Of Fire & Flames
55 Photoshop Brushes Of Energy Spheres