The example below is for rendering an eBook in PDF format with a Word 2010 source file and Adobe Acrobat. You can use other pdf creators and other software to make PDFs.
Print or save the document.
Create a pdf file by either selecting File -> Save As -> and then selecting pdf as the file type or by printing the document and selecting the pdf driver as the printer. Depending on what is installed on your machine, these two methods can yield different results because they can access different pdf creator programs. For example, in this picture, the printer driver brings up the Adobe Acrobat creator.
Make sure your settings are correct.
What fonts does your document use? If you use anything other than Times or Times New Roman, Courier, Helevitica or Arial, Symbol, or Zapf Dingbats, you might need to include the fonts in the file. In the above image, if you click on edit (number 5 in the blue bubble), you can get to the settings.
Other concerns when making the pdf file include:
Add other pages as necessary.
Select the initial view
Save the pdf