When you first start Web Content Studio, the tabs across the top look like this:

You will notice there is no Editor tab, and  a few people panic.  However, this is completely normal, since the editor tab is there to EDIT an article, and when you open WCS, there is no article open.

When you add a new article, or open an existing one for editing, the Editor tab appears:

Also, related to this is a button on the Keyword Spider:

When there is no editor tab (i.e. no active article), the “Add Phrases to Article Theme Lists” is deactivated.  That’s because there IS NOT ARTICLE to add them to.  As soon as you open an article, or create a new one, this button will become active.