When you create wiki in Windows SharePoint the first thing you normally do is delete the two default items that SharePoint creates for you. You then start populating the wiki with your own items as show below.
This means that when you click on the link for your wiki you will be taken to a list of items like that show above. However, what happens if you want to come to a landing page and from there select different options to perhaps make it less confusing for users?
All you need to do is create a new item in your wiki called ‘Home’, like shown above. Now whenever anyone click on the link for the wiki library they will see the ‘Home’ page displayed.
If you click on the name of the wiki in the breadcrumb navigation at the top of the page (in this case Knowledge Base) you will again see all the items in your wiki.
So to create a default landing page for your wiki simply create an item called ‘Home’.