You can insert links in two different ways:
You use external links when you want to link to another website, and you use internal links when you want to link to a page inside your flipbook. By utilizing this you can easily help your viewer to jump to the section in your flipbook that is relevant to them.
This is especially useful if you have a big publication with many pages as you can use internal links to create a table of contents to optimize the usability.
These internal and external links are easy to create in the Paperturn system (where you customize your flip book after you upload your PDF). When you insert a link you can choose how big the click areas need to be.