I like what you've done so far. The planet looks good, I think you need to mess with the filters a bit more to give it the look you're going for, but I have to object to the background.

There's no way that you'll ever see galaxies like that in the background at the same time you are seeing the planet. The light from the planet would completely washout the faint light that the galaxies would give off. That's assuming you could find a distance to image this planet at which would also give that magnification to the galaxies anyway.

I know galaxies and nebulae look cool, every "syfy" image out there has them, but you're far better off realism-wise if you can find a starfield where all the stars are just pin pricks and if there are any nebulae they are about the size of one of those galaxies in the background. If you have a nebula that fills up the background it would be so faint and diffuse that you'd never be able to image it except with time lapse photography.

Basically, if you want a background to put a planet on, it should probably look a lot like what you can see from the earth without a telescope.