To enter a new entry to the Guide, start by pressing the "edit" link on the top of the page. You get to the editing page of this page. Don't edit the existing text, just add
* [[Title of your entry]]
and click "Save page".
This adds a link to a page that you can now create. You can see the difference to the pages that exist by the color: existing pages are linked with blue and the new link is in red.
Click on the link you just added. You enter to the editing page for a new entry - this is the place where you can write your tip or article.
This is the easy way. You can be more creative and add additional links and pages to existing pages - the new pages do not neccessarily have to be added by creating the link here.
You can get additional help to editing by clickin on the "Editing help" link under the textfield in editing mode.
Click edit and simply add your link like this: [[your link]]. After that you can click on the (probably) red link, and start writing. Don't worry too much about style, spelling or wiki syntax. Just type whatever you know as a hitchhiker about that place! Other people will make sure your addition will be integrated into the site.