There are three types of linking you can do from a tiki wiki site, links to other wiki pages within the site (wiki links), links to external websites, and links to other wikis.
Here is a shot of the editor. The first circled icon is to insert a wiki link, the other is to insert an external link.
You can use the wiki markup language to insert a wiki link by putting the name of the page in double parentheses, i.e. ((text)), where "text" is the page name. If you are using the WYSIWYG editor, you will make the link whatever you'd like and select the page name from the list, or type it in if you are going to create the page later. So, in this example, the name of the page might be "text" but you might want to say to visit the text page, click here with click here being the link.