Most authors are familiar with the traditional, print-media linear mode of thinking. You have an introduction, then chapter one, then chapter two, then a conclusion. The reader reads in a straight line, moving from one point to the next in a fixed order.
The Web is a new media, a hypertext media, a true web instead of a straight line. Readers can read your pages in any order. They might do an Infoseek search and wind up on one of your "lower" pages, not reading any others. Someone may like a particular page of yours, and link to it, so readers get to your page from that person's page. The reader does not necessarily start at your intended "main" page.
Back, next, previous, last, return to, and other such directional terms are leftovers from linear thinking. They don't apply to the web.
Here's an example. Say you create a restaurant guide, and you have pages for Italian, Cajun and Chinese restaurants. You think everyone will start out at your guide page, so you have "back" and "next" buttons on each of your pages. Well, someone else on the net creates a Cajun guide, with links to Cajun language, Cajun music and your Cajun restaurant page because they liked it so much. Now some reader is reading a Cajun guide, jumps to your Cajun restaurant page, hits "Next" and winds up on Chinese restaurants. What the hell? "Back" and "next" are from the author's point of view, not the reader's.
But you want the reader to be able to get to your main page. No problem. Add a link to your main page. You are not linking to "Back," or "Next," you are linking to an Italian restaurant guide or whatever. Make a link and call it "Italian restaurants." That way the reader knows exactly what will happen if they follow that link.
"Click here" is another awkward result of unfamiliarity with hypertext thinking. Number one, not everyone in the world is using a mouse. "Click" is redundant for people with a mouse (they know how to use the web, trust me) and wrong for the others. Second, "here" is not what's on the other end of the link. Your links should say what's on the other end of the link. If you have a restaurant guide, say, "I have a _restaurant_ _guide_", not, "Click _here_ for my restaurant guide."
Page by Ken.