The Acoustic Regular Slinky strings that boxboy suggested are pretty good, I've used them before myself. D'Addario also makes excellent strings at decent prices. If you want a little more string life, the Elixir line offers polymer coated strings that last quite a bit longer that uncoated, but they lack the really bright tone that a good set of phosphor bronze strings gives. I personally use Elixir, only because I don't play my acoustic nearly as much as my electrics, and they still sound good enough to make me happy. I've had the same set on mine for a little over a year and I'm just now ready to change them. Your mileage may vary and all that.
Strings are a very personal choice, and you'd do well to try a few different brands to see what you like the most.
As far as help with restringing - plugging "restring guitar" into Youtube's search box will generate more results that you'll even know what to do with.