Idiot guide to my derailleur

Hi I know the answer is already here, but if I read to much I will think I can fix everything, and that's not good.
My Campag Veloce derailleur has shifted a few mm, from the inside pushing out, when in the big ring, so it's now noisily rubbing against the chain.
I have about a 10% success rate moving it back a couple of mm's, but the other 90% of the time I've managed to turn my Bianchi into a unicycle!!!!.
So please in words of one syllable what needs adjusting, how far, what way, etc.
Think of it as explaining your DVD player to a deaf grandparent.
My Campag Veloce derailleur has shifted a few mm, from the inside pushing out, when in the big ring, so it's now noisily rubbing against the chain.
I have about a 10% success rate moving it back a couple of mm's, but the other 90% of the time I've managed to turn my Bianchi into a unicycle!!!!.
So please in words of one syllable what needs adjusting, how far, what way, etc.
Think of it as explaining your DVD player to a deaf grandparent.
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campag instructions are here...
http://www.campagnolo.com/jsp/en/doc/doccatid_4.jsp
or the all-in-one document...
http://www.campagnolo.com/repository/do ... 202011.pdf
...see page 51, it's the g screw
there's also a chance the mech hanger is bent