For creating a page in a wiki you can click on the 3 dots at the top of the pages & then choose "Add new page" & as for the content of the page Pafton mentioned the links I wanted to provide
Also, depending on whether the wiki enables Discussions, the add new page button may appear as a folded paper icon instead of a menu on a dropdown content appearing when you hover the 3 dots buttons. For instance, here is how it looks like on the SOAP wiki:
The same goes when you are on Discussions. Instead of hovering the 3 dots, you should just click the folded paper icon:
I've edited your post title to make it clearer. In future, please make your post titles reflective of what you're seeking help with, since our guidelines require it. 🙂