If your webbook is to have limited access, that poses a slight problem. First, you want to deny access to anyone who hasn’t paid. At the same time, you want to give them an opportunity immediately to see a sales pitch for the book and buy the book (purchase a password). Second, you want to give visitors who have become users (by paying for a password) immediate access to the Table of Contents (TOC).
There are multiple ways to solve this problem depending on various marketing strategies. The simplest way is to place two buttons (links) on the cover. One button named Login would be for paid customers and will take them to a simple login page where they enter their password get immediate access to the TOC. The second button, labeled Buy the Book, takes visitors to a sales pitch about the book and a checkout page where they can complete the purchase.
Password Protection
The easiest password protection is to simply make the folder in which the webbook files (webpages) are stored inaccessible without the folder password. This requires no special software, only an election in your web host file management (very easy to do). This technique uses one password. Everyone who buys gets the same password.
The advantage to this technique is that some customers will give the password to friends who will then have access without paying. This is a loophole in your system that will promote stealing without actually permitting it. If you believe in giving away free books to promote sales, as I do, then this password scheme becomes a marketing technique too. On the other hand, if you don’t want anyone stealing the password (to get a free book), you will think of this as a disadvantage.
The downside is that someone may post the password on a public website somewhere thereby permitting a huge number of people to, in effect, steal your book. This may be undesirable (or not) if it happens. If it does happen, it may be difficult to repair the damage. You would need to change the password and then inform all paid customers of the change.
Membership Software
Another password technique is to issue a unique password to each paid customer. This takes a software system, but such systems are readily available. One technique is to use membership software. A user pays for a membership and thereby gets a password providing access to your webbook.
If a customer’s password is posted on a public website enabling people to steal your book, the repair is easy. You need to change just the password for that one person.
Final Word
Keep in mind that passwords are inconvenient for users. If there is a better way that’s appropriate for you to control access to your webbook, you might want to consider it.