I’ve seen a number of blog posts about setting the default homepage in a wiki library, and most of them offer ways of accomplishing this task through PowerShell or through SharePoint designer. Although I have become an ever increasing fan of PowerShell, I still prefer to stay away from it unless I’m trying to do something fairly complicated or I need a script that I can run over and over again. If all you need to do is set the default homepage in a wiki library, there is an easier way!
First, navigate to the wiki page you want to use as the default homepage. Then click the Page tab in the ribbon. In the Page Actions group there is a button called Make Homepage. Click it. A confirmation displays informing you that you are about to change the homepage. Click OK and you will have a new homepage for your wiki library. No PowerShell required.