Is the pool of fluid definately brake fluid and not just water from a leaky door seal?
How low did the fluid get? Low enough to let air in the system?
Have you got an brake fluid/clutch leaks anywhere?
What condition are the discs, pads, shoes and drums in? The grinding could be coming from them.

To be honest, as you have already admitted you are "totally crap with cars" you MUST take it to a good garage or at the very least a good home mechanic as the brakes are the most important part of your car and it sounds like a death trap at the moment!