Gimpdome

First, welcome to the forum if I hadn't welcomed you before.

A border well this is my favourite method:

1. Add a new layer above your sig
2. Fill with black (if you want a black border)
3. CTRL+A (or Select All)
4. Select > Shrink   ...  I normally use 1 or maybe 2 pixels.

Tada a border. 

As for the sig. It looks good though there is room to grow for sure. We all have room to grow. Check out the depth and contrast tut. You can find it here.

you should see the tutorial. I will look into it.. either way you should be able to find the tut here on the forum.

top ones before and bottom ones after. is it better? i also have a question, when i rescale a image to half its size how do i get it to be detailed again... cause its always messed up

These are just my opinions nothing more take them for what ever you want.

Your render is way to dark. It is very hard to make out what it is. The fog and bluring over the bottom half of the render really distracts from the render itself. The lines created with motion blur on the render appose the direction of the flow created in texture of the background. This creates a very disjointed image.

The color of the background on the left side of the sig clashes with the render and  right side of the sig. This creates a very abrupt transition. The lighter coloring on the right works well because it blends well with the lighting on the render.

I do like your background and i think the render would work well with it but it needs to be lighter.

when i rescale a image to half its size how do i get it to be detailed again... cause its always messed up

You might want to check into Liquid Rescale or use a process of stepping your scaling.

Say you want to reduce the image by 50% you could do one rescale at say 85% than apply a small amount of sharpen say 10. Than step the image by a scale of say 85% again (The last step plus this one = 30% reduction so far) sharpen it by 5 to 10. Than step it one more time at 80% (making 50% reduction over all) and some minor sharpen say 5. Pay attention to your sharpening because if you use to much you will get a very bright lined or halo effect. If you don't use enough than you get a blurry distorted look.

There may be a script out there to do this faster, but it is not hard to do manual and in the end you would have more control over the output.

off topic --

, but i wouldnt get g'mic as it umm has extra features you dont really need.

I agree and disagree with that.  It does have a ton of features and it can be pretty over whelming but the more you use gimp and the more you create with it the more you use those other features. Plus one would never know what features they would need or not need if they did not try it out.

G'Mic has some pretty useful features that you can not find any where else for Gimp. One right off the top of my head is the Exclusion layer. Darth and i tried for a while to duplicate the effect with out G'mic nothing we came up with looked like the effect exclusion layer creates for an image. At least not in a simple to explain or use way.

is the lighting better now?