Just an amazing photo of a nebula, showing how awesome 'space dust' can actually look. This is a real visible-light image as well!
Here's an image of some 'spectral lines' that have been red-shifted. This is one way we can tell that things are moving, not just that they're a redder-colour than we'd expect. Remember these lines come about because of electrons jumping around inside an atom when it gets heated.
In this case the gaps mean light is getting absorbed by electrons, so you get dark spots. If you want to know what lines each element produces you can look at the light that they emit, say when you make a lamp using that element:
These patterns of lines work like a 'fingerprint' that means you can look at a star's light and say, hey there's probably hydrogen and neon in this star. Here's an example of what an actual spectrum might look like for a scientist to work with. The higher the line on the graph, the brighter that light is. The wavelength of the light is along the bottom, with a longer wavelength meaning the light is more red.
You can see lots of little bumps that show emission, and lots of dips down that show some light is being absorbed. Maybe there's dust in between us and the star, or maybe the star's own atmosphere is absorbing some of the light.