Can someone explain this whole analog TV switch?

Well firstly you need to buy a digibox, or a new TV, which will almost definitely have free-view now.
This will probably help with all your questions (it’s the official site for it)
http://www.digitaluk.co.uk/

you need to be buying equipment with the little pink digital tick :)
it’s happening because
“Switchover makes it fairer for everyone. Currently, one in four UK homes cannot get digital TV via their aerial and many still cannot receive Five. Only by switching off the existing “analogue” broadcasting system is it possible to boost the digital signal and get it to parts of the country that can’t currently receive it”

I live in Canada. Any advice for here?

@Ukasaka, this is something that’s only happening in the UK as far as I know.
But I would have thought similar things apply, it’ll be the same reasons why they’re doing it and so on.

check out wikipedia page

It’s happening in the US as well.

Here is information on the switch in Canada, which does not occur until 2011.