Hi there, and welcome to the forum.
Yeah, I don't know why instructions in kits are so bad. For that matter, I'm getting a bit frustrated with the standard offerings in the homebrew market these days. Maybe I'm just tired and grumpy!
Anyhow, have a read of this:
http://www.thehomebrewforum.co.uk/viewtopic.php?f=30&t=4022 thead. It's a really good guide.
Generally speaking, a good ale fermentation will be done in about 7 days. You'll want to try and keep a consistant temperature over this period, preferably not too warm. 19 to 21C is about the sweet spot for English ales.
Many of us will let it go a few days more to let the yeast "clean up" the beer. Look up "diacetyl rest" for more info on that. After all that's done, you can cool the beer before packaging (keg or bottle) and this will help the yeast settle to the bottom, clearing your beer.
If you're using tap water, you definitely need to treat with campden tabs (potassium metabisulfite). It will remove chlorine & chloramine, which if left in, can produce off flavours in the finished beer. These can range from cloves to medicinal type off flavours - not what you want!