Plenty of threads on this elsewhere Neil, but it's pretty easy to start small and work up.
So I'd start with a small tub/barrel....
Fill to the top with water, add a few tablespoons of washing Soda crystals, not bicarbonate!
Find a piece of clean steel and fasten it to the inside running down to the bottom, I usually put this inside a piece of plastic waste pipe with holes in. This stops it shorting out on the piece you are cleaning.
Find either a good battery charger, or a good battery with a reasonable charger. You need a good 12v supply.
Connect the positive to the clean metal with wire/crocs clips. Try not to let the clips go into the solution.
Connect the negative to the dirty piece and lower it into the tank.
If you have a reasonable charger the current will move up to around 1A depending on the size of the anode and piece being cleaned.
After a few mins you should see bubbles coming from the piece being cleaned, after an hour there will be a brown scum floating on the top.
The rest is patience, some pieces clean pretty quick, some take days/weeks. You have to keep cleaning the anode and sometimes help by scraping some of the loose paint away.
I think that kinda covers the basics
