(from link above... see step 2 for how to find someone willing to format your book)
Easy as 1-2-3:
Sign up for your free account. Your confirmation email will summarize your next steps.
Format your manuscript as a Microsoft Word .doc file per the guidelines in the Smashwords Style Guide,or, if you don't have the time or patience to do it yourself, send an email to email@example.com to request "Mark's List" of low-cost Smashwords ebook formatters and cover designers.
Click Publish and follow the simple steps to upload your book and cover image.
The following two links are listed on the page above. The Marketing Guide is very good reading. The Style Guide is the details of how to format the Word doc.