Expand the HTML 1 tutorial based on confused areas last night.

There were a couple of typos in the HTML 1 tutorial, as well as some parts which tripped up the students I worked with last night. I've cleaned those typos up, added some explanations for confusing bits, removed some
technical language in favour of plain English, and simplified some other sections.
Im not averse to removing it, but it's used in the first HTML the student writes (within the <body> tag) and it's not explained anywhere.