I can see what's happened - you overfilled the demijohn. When you're starting something off, fill the demijohn only to the shoulder (where the main body begins to curve into the neck). That gives enough room for any initial frothing to occur. If you fill it right up (as you have), the foam doesn't have time to break down before it rockets up the narrow neck. Only when any foaming has died down should you top up the demijohn - but you should still leave a gap of, say, three-quarters of an inch below the bottom of the airlock bung to prevent any infection by contact.
However, you're usually safe in just washing out the airlock at regular intervals. It will become less Quatermassy soon.
Incidentally, I'd put it the right way up or all the wine's going to pour out.
Mike
but being a total noob about it can I use bakers yeast as that's all I've got? Will it take longer or just produce a less alcoholic brew, sorry for the spanish inquisition I just haven't a clue. lol, lastly ( well for now anyway 
) is it 'done' when it stops bubbling or is it just guesswork?
