On most Yahoo! Web Hosting accounts, you can add as many pages as you like.*
If you plan to add a lot of pages to your site, keep in mind that too many links in your main site menu (navigation bar) can look unmanageable to site visitors, so we recommend limiting your main navigation to 10 pages or fewer.
*Note: If you are using Yahoo! Web Hosting Basic or Advanced, use this help page to learn about account restrictions/limits.