How do I create a hyperlink in one Idea to another Idea ?

There are two ways to create links between ideas :

1. The first method is named "associations" between ideas. Select the idea in which you want to create a link, open its properties, and select the "Associations" tab, click on the "add" button in the "other associated ideas" section. This opens a selection dialog : select the ideas to which you want to link and validate.  Associated ideas (links) will be shown in your page, according to the structure template option (expert mode).

2. The second method is a link in the idea text. You have to activate the "Normal" view (the WYSIWYG HTML editor), and click on the rightmost icon (a double chain). Select the ideas you want to link, and WIT will insert all the links for you. You may edit/change the inserted text (by default, it is the idea titles).