If you are new to wikis, you might wish to practice in the sandbox until you get the hang of it.
To start a new page, all you have to do is click on the "edit" button above and then type the title of your new page with double square brackets [[ ]] around it in the box that appears. Once you have typed the title, go to "show preview" below. When the preview appears you will see your new title displayed in red like this: your new title. Click on the red title. Et viola. You have a new page. You can then add content to it. Don't forget to save it. You can go back and edit it anytime.