There are two ways to prevent search engines from indexing your ScreenSteps content:

1. Exclude your site from search engines (as explained in this article). This does not require users to login to view your content but tells search engines that they should not index your pages.
2. Make your site private. A login will be required to view any content and no search engines will be able to index your content.

The article will show you how to configure your site so that search engines (e.g. Google, Bing) do not index your knowledge base, and present it as a search result.