Buttons like these can be done by adding the script:

<span class="wds-button">[[Page|Display text]]</span>

(don't remove [[ ]])

Self-made variant:

User:Oot42/Sandbox-3?oldid=3841720

A button to create a page can easily be made by putting the following into an article.

<inputbox>
type=create
</inputbox>

See Help:InputBox for more info on things you can do with these. Though, if you want more, you will need to make your own button as the other replies hav stated.

Well, that's not a button. That's an input form. ;)