I'm a bit confused about how the fuel manages to get from wherever its being stored in a spacecraft into the engines, seeing as it is supposedly solid and so seems like it wouldn't be easy to move. could anyone explain how the solid propellant works for this?
The solid propellant is stored in the engine, so it doesn't have to be moved.
The engine consists of a large cylinder that contains the propellant (indicated as 'grain' in the image, but it's a solid block with a grainy structure), with the nozzle at one end of the cylinder.
Here's one segment of a Space Shuttle solid booster, with the void down the middle clearly visible:
The propellant is shaped as a hollow cylinder: the void down the middle is exposed to the elements. When the engine starts, this surface is ignited. The hot gases escape down the central void and out the nozzle.