1 - First off, it really doesn't matter what size the file is for an epub, so it's easiest to create an 8.5x11" page, since that's the default setting. Just make it one page for now rather than guess how many pages it will be.
2 - In the master pages, set up a text box.
3 - Place the text while holding shift on the first page. This should automatically create all of the pages necessary to hold the text.
Tip: With InDesign, if you make each chapter it's own file and then create a book using those files, it will automatically create a table of contents for you. Each chapter will be titled whatever you name the files.
4 - Once you've placed the text, there may be a problem with the tabs, as in they disappear. The only way I could figure out how to fix this was to manually go through the file and re-add the tabs.
EDIT - Well, I was just reading a guide and apparently all I had to do was go to Paragraph Styles>Indents and Spacing>First Line Indent and change it to .25 or .3 inches. Yup, that would have saved a lot of time if I'd known earlier.
Tip: If you just press the tab button on your keyboard, the ereader won't be able to recognize it and the paragraph will remained justified to the left with no indent to indicate the start of each paragraph.
5 - The Paragraph Style should also be set to keep the font style, font size, and the justification consistent for each paragraph. Have these settings changed on the same Paragraph Style as the Tab and all of your paragraphs will be consistent.
Tip: To check what the settings of your Paragraph Style is, just go to Redefine Settings>General and the settings will be listed under Style Settings
6 - Go through your file paragraph by paragraph one more time, in order to make sure no tabs or styles are messed up.
7 - If you're uploading only one large file, press export as epub. If it's separate chapter files, build a new book (File>New>Book) and then press Export as epub.
8 - Cross fingers and hope that it opens correctly on the ereaders (Check it before uploading to publisher!)
Hope that was helpful, if not I know it will be for myself when I'm trying to create my next book.
BTW, I just grabbed the Smashword Style Guide for free off their site. It is specifically for Smashwords and creating a basic .doc document, however a lot of the tips seem to be really good no matter what program you're using. Haven't read it all yet, but definitely looks useful for any newbies to the ebook game.