If editing the HTML only changed the top of your page, it may simply be that you needed to scroll down past all the text, to the bottom. Meaning, if you got a Prev/Next to appear, it might simply be a matter of moving where you'd placed them. HTML Code works by opening a tag like <something> which affects what comes after until you close it </something> using the same tag with a slash. (Replacing "Something" with "i" there would have italicized the text.) If the tags are not nested properly, sometimes the system tries to interpret, and doesn't do a good job of it. (FYI, there are some rare tags that don't close, like a hard return or "break": [br/] ) I got nothing on CCS.
I can offer what I do with blogger. I drop a table into the bottom of the chapter. It looks like this:
<table align="CENTER" border="1" style="height: 27px; width: 500px;"><tbody><tr>
<td style="text-align: left;">PREVIOUS</td>
<td style="text-align: center;">[a href="http://WebSiteIndexPage"] INDEX [/a]</td>
<td style="text-align: right;">NEXT</td>
The table dimensions are in pixels. TR (table range) is cells down (rows) while TD (table domain) runs across (columns) - yay for math terms. The A HREF is an Anchor reference, aka a Hyperlink, which I've hard coded to an index page, and for me is the same each time. (*NOTE: It should have the same style brackets, but the forum was smart enough to literally change that code into a dummy link, so I modified it to use , so you can see it.) You'd use that same "A" code to link the PREVIOUS and NEXT parts of the table to the webpages where those chapters are. In Blogger that can be done by simply highlighting the words (outside of HTML), clicking the "link" button, and entering (pasting) the website.
If anyone knows a better way, feel free to chime in. It's not much of a pain for me, dropping it in each time (particularly with the Index page pre-coded in), but if there's more efficient methods, probably better that Calypso learn those first.