I'm editing this MediaWiki Wiki (not Wikipedia etc.) , and I want to have some fancy effect. On Wikipedia there are templates which sorta-kinda-do what I want - but this Wiki doesn't seem to have them. How can I determine which templates it actually has?
Because templates are just normal pages with a specific type of content on them, there is no one set-in-stone way of finding a list of templates. However, the majority of MediaWiki sites will use a Template namespace for keeping templates together and easily implementable.
To get a list of all pages within a given namespace, go to Special:AllPages; at the top, select the namespace—Template, in this case—in the respective dropdown menu, then click the "Go" button (or hit your Enter/Return key). Do not enter anything into either text field. You may also want to check off "Hide redirects," as redirect pages do not have template content.