Reflections are very hard to make with any image editing program. If you want your plane to be more reflective, it's easier to make the paint more reflective in the simulator. You can add an 'alpha channel' to a plane's textures by using a program called DXTbmp. The alpha channel works with greyscales. The darker you make it, the more reflective the textures.

If you want to make reflections in photoshop, things will get more complicated. You have to play around with layers, opacities, lighting, angles and the liquify tool.

For instance, if you want to make a reflection in water of a plane that's flying over a lake or something, you can't just cut out the plane and copy it it then mirror it. Then the angle would be off, it wouldn't be distorted by the waves and it would look like the lake is a perfect mirror.

If you sure you want to do this, let me know and I'll give some more tips.

No problem. Have fun.