Is there a training manual for the Trader Workstation?

Overview: 

Yes, IBKR provides a Users' Guide for the Trader Workstation (and also the Web Trader).  This Users' Guide can be found on the website via the Education > Documentation menu item.

Background: 

You can access the TWS User's Guide at the following link: TWS User's Guide.  There is also a printable version available but be aware that it is very long should you decide to print it out.  Once the online guide is loaded, you can navigate through the guide with the "Contents" or "Index" tabs.  For quick access to information on a particular issue you can use the Search button found at the top of the page.