Internet – The omnipresent wonder invented by Al Gore gets a capital I.
Intranet – No capital.
Web page – Another capital letter. It’s two words.
home page – Two words.
email – No hyphen. Yes, it used to have a hyphen but it was dropped.
e-business, e-commerce, etc. – These have hyphens. Go figure.
But in general, the rule of thumb is consistency. If you want to spell webpage as two words go ahead. Just be consistent.