You could try Electronics for Dummies
(The link is for the UK Amazon site, so if you're not in the UK, just search for it on your local Amazon or online bookstore).
It helped me to understand the individual components that were talked about in diagrams.
In terms of that MagPi article, you'll want to look at the stripboard diagram rather than the circuit diagram at the top. The stripboard diagram shows you what to solder more clearly. The other thing is to watch out for projects with "Fritzing" diagrams - these are even clearer.
Fritzing is a piece of open-source software that allows clear and colourful diagrams. http://www.fritzing.org
Apart from that, you could try asking on the Raspberry Pi Foundation forum if you need help on specific projects, particularly those from The MagPi.