I want to read!
That's great! There's a page that allows you to read all our pages. Meta.
You can also go to a random page. Disclaimer: It may not be very random!
I want to contribute!
Then, just find a page as described in the "I want to read" section, press the "Edit" button in the top right, and start contributing!
If you want to create new pages, type the page's name in the search bar and press Enter. A search menu will appear. Below it, there will be a red link allowing you to create the page. Click it, then click "Create" in the top right. Then, just start contributing!