Wow - I'm afraid I've just spent half an hour using a number of potential options, from HTML, to BBCode to simple copy and paste... It would appear that not one of them works on InfoBarrel...
Having said that, I'm finding constant error messages on InfoBarrel today and have been unable to save/publish any articles. Maybe something to do with pending upgrade?
Copy the URL of the page you want to link to.
Within the editor, highlight the text you want as your anchor text
Click the link button (looks like a chain)
Paste the URL into the box
Close and save.
You can do the same thing in the forum, just highlight some text and the Link button becomes available. There is also an unlink button beside it is you want to break a link.
Yes you need to publish the article after any changes. If you are modifying an existing article it stays the same until your changes are approved.
Like Jade says, it won't show up in your article until after published/approved.
But if you ever want to check to make sure the link works before you resubmit it, hit the save and preview button. Once in preview you can click the link and it opens from there.