Oh yeah no problem. Pretty much the different thicknesses of paints you can get by thinning them can give all sorts of different effects, and there's a few sorta major categories of paint depending on how thin they are. Normal paints straight out of the pot, Brushable paints which are thinned slightly to brush on smoother, airbrushable paints which are thinned more significantly to go through an airbrush, and then wash paints which are thinned very significantly and used to weather stuff by being 'washed' over the whole piece then cleaned off.
There's also two major types of paint themselves, acrylics and oils. Acrylics can be thinned with regular water, oils must be thinned with oil solvents such as mineral spirits. There's also laquers which are sort of a type of oil paint, but they're mostly specialized spray paints.
But yeah, weathering, like you're doing there on that big chrome section in the center, are almost universally done with washes. Very rarely in real life will you see weathering that is distinct brush-like strokes, it's almost always a more diffuse dirt. The exception are scuffs and such, but those should be a separate layer of weathering done after washing.
Here's a video that'll show some basic acrylic washing [MEDIA=youtube]ybrUVKmEUew[/MEDIA]
Check out a lot of his videos, they're great resources.
