In any case, to change the nav, you will want to edit the '''MediaWiki:Sidebar''' page. (e.g. http://example.com/wiki/index.php/MediaWiki:Sidebar) The right to edit this page is normally restricted to administrators, so if you want to delegate the responsibility for this, you will want to look at the user permissions system. There are rules and conventions which apply here, and you can [[mw:Manual:Navigation_bar | find more help in the documentation]]. In case you are going to change the location of blocks like the '''search''' box or '''toolbox''' (which normally show up in the sidebar) by making a custom theme, you'll want to coordinate those changes with the sidebar.
It is possible, using JavaScript, to customize the '''search''' or '''toolbox'''. (We did this for the [https://www.mediawiki.org/wiki/Extension:Html2Wiki Html2Wiki extension]. See the article here on [[MediaWiki/Toolbox]].
== How to make your own skin ==