The easiest way is to create a link from the parent page. You should find there are sufficient categories to find a suitable home. Edit that page and include a link to your new page, for example:
* MyNewPage – My page on how to do stuff
The * simply makes the line part of a list - most of the category pages are lists. The – creates a dash, and you can of course change the description to suit your needs. The page name must have at least one capital in the middle, surrounded by lower case letters. This is called CamelCase.
Having edited the parent page, save it. You will be shown the revised version you've made. Then locate your new line and you should see
Where the ? is a link. Click on it and get editing your new page! Once you've edited the new page and saved some content, all the references to it will be automagically turned into links to that page.
The above is quite wordy, but once you've done it a couple of times, editing pages is dead easy.
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