How do I download the book?I am not able to read the book.
Downloading documents and music files is similar all over the web. Since you said you couldn't "read" the book (not unable to "hear" the book) I assume you're downloading a document. Most of the time, these are in PDF files, although you can download them in Word or other word processing files. Once you have paid for the book (unless it's from a site offering free services), you should be able to open the document on your computer and read freely at your leisure.
One thing you will need to check is the compatibility of your computer system to the system (program) used by the site from which you are downloading. For instance, if you are using Microsoft Word 98, and the site you're getting IF TOMORROW COMES from is using Windows Vista, it will not be compatible. Your system can not support a newer version.
In this case, you need to save your document as a TEXT file so that you may read it on your computer. The formatting may be messed up a little, but you will be able to read it.
Check with the site from which you are downloading the book and be sure your system is compatible with theirs. If this is not the problem, I suggest you contact that particular site for customer service/technical assistance.