This is how I create new wiki topics here... there may be a smarter way, but I haven't figured it out:
type a WikiWord (multiple words in camel base), in the parent topic you wish to create a child topic from
save the page
if the wiki word hasn't been taken yet, there should be a small ? mark beside it
clicking it will bring you to a new edit page
type something and save the edit page
you've now created a new topic
Sidenote, if you do NOT want to create a new topic when typing something in CamelCase, simply append < nop > (remove spaces) in front of it (or just hit Edit below and see it in code...)