Others answered the how perfectly, but I can give you the "what". Since you mentioned polygon based engines I'll try to speak in those terms.
Backgrounds: Backgrounds are comprised of an unlimited number of layers. Each layer is a repeatable 256 color or 24bit RBG color image with any number of special effects applied. The play field is another layer, made up of three tiles. It's all explained
here, and less complicated than it sounds.
Lighting: OpenBOR supports a single realtime light source out of the box. By default this controls angles of shadows and reflections. You can also configure it to add glow effects, clipped tinting, fading, and so on. There's no pixel shader, but you can can simulate the same end result. If you want, more light sources can be added, but you'll need to script them manually. While it's possible to do this at the sprite level as
nsw25 said, it is neither required nor recommended. Instead, it's handled on draw (what you'd call render) by a series of real time graphical adjustments we call
drawmethod
The short version is stuff like SOR4 is easy money for OpenBOR, but don't try to compete with that stuff out of the gate. Worrying about what the engine can do when you don't even know how it works yet is getting the cart before the horse.
Crack open a basic module and play around a little. Adjust some things here and there just to see what happens. Ask us questions about things as you go. Pretty soon you'll get the hang of it and be on your way.
DC
PS, since I hadn't said it yet, welcome to the community
Wombat2112!
