Texturing help please

Could someone please, please tell me how the person on this thread http://blenderartists.org/forum/showthread.php?t=194770 has made the edges rusty?
I need to know how because I would like to make the edges of the gun im currently making look scuffed up (like wear and tear). What method is used for this?

Also can someone please tell me how I can specifically add bump mapping to certain areas of an object? everytime I make a bump map blender tries to stretch or copy it over the entire object:spin: I just want the bump applied to one area if you get my point.

Any help would be just fantastic, thankyou.

The first thing you need to do is UV-mapping. Once you have created an UV-map for your object you have to make a texture for it. The rusty edges on the skoda, for example, are simply hand painted either in blender’s 3d texture paint, or in your favourite image editor, like gimp.
Simple UV-mapping tutorial: http://www.youtube.com/watch?v=FI859_0-rrU

A good way to have a texture applied to only certain spots of the model is to use a mask or stencil, as it’s called in blender.

Once you have UV-unwrapped your model you simply add a new image for texture. The image will be completely black. Now go to texture paint mode and paint the areas white where you wish to apply the texture/bumpmap.

Save your image and add it as a new texture to your material. The mask texture should be above the texture you wish to apply but below everything else in the stack.
Set mapping to UV and check the “RGB to intensity” and “stencil” options.
That should be it…

your an absolute star! Thankyou very much for the help.