DC wrote
the orange warning light (top right) comes on now and again, and when I opened the engine oil cap and looked in, to me it looks like its empty, and I know thats not good! When I bought the car, it came with a half drum of Engine Oil, do I just put that in and if so how much
You sure it's not the windscreen washer bottle light?
when I opened the engine oil cap and looked in, to me it looks like its empty
You'll be able to see oil on the inner surface. Use the dipstick to check the actual level. Don't mean to sound condescending but don't fill up the oil, to the point where you can see the oil level through the filler cap.

If so you'd have several litres too many in the sump, which is almost as bad as too little oil!