That's because your wiki is new and not having enough content. In order to have your wiki show up in search, you need to have more contents and more contributors. You can read this help page of how SEO works. You might want to read this help page as of how to attract new contributors. 

How many pages are required??

And how can I attract contributors if my wiki is not on Google?

by going to the wiki directly rather than from a search engine. An example is changing "community.fandom.com" to "wikiname.fandom.com" in your URL bar.

As a general response - try creating articles on some of the middling/more obscure relevant topics, and perhaps overview articles.