Bike Problem?

Well I've started getting out on my bike, just across fields, along footpaths etc (the joys of living nowhere near the mountains) and I've noticed that the chain and the derailleur (sp?) if thats the right term (I'm new to this!) are not alligned but I'm not sure where this is meant to be the case although I seriously doubt it. I have put lines on some pictures to try and help show the scale of the difference but I'm not sure if you will be able to see them, anyway heres the pictures and any advice would be much appreciated, thanks.