Thanks everyone for the replies. I'm probably going to try it again tomorrow.
As for tools, I don't have many. I have the screwdriver and an adjustable wrench, but that's about it.
I don't have a bike stand, so I have to work on the bike either sideways (like in the pic) or upside down. The bike's been/being stored upside down. The shifter is in a strange position on the bike, so that when the bike is placed on the ground upside down it is immediately knocked out of the highest gear.
BTW, I just noticed that in the pictures the claw for the derailleur is in the incorrect position. I have fixed it since, but the chain is still obviously twisted and tangled up.
This is probably one of those times I'd take the bike to the local bike shop, but the nearest bike shop is 30 miles away and the bike doesn't fit in my car. So...
