If you're looking for a manual for the iPhone, one of the better resources I've found is the iPhone Users Guide. It's formatted specifically for iPhone, so if you try to view it on a computer, you will not get the same result. Punch in the URL on Safari on your iPhone, though, and you'll get a very helpful resource.
For whatever reason, I wasn't able to find this guide easily via Google...I had to go back and find it on my personal iPhone (where I have it bookmarked). I'm not exactly sure how I stumbled upon it in the first place, but I'm glad I saved the URL. The URL is:
Hope you find it helpful. It's definitely a good resource to link to for anyone you know who is new to the iPhone.