The Avalanche quick start guide is in the Layer 4-7 Application directory, e.g. C:\Program Files (x86)\Spirent Communications\Spirent TestCenter 3.90\Layer 4-7 Application\docs.
More information is found in our online help. From the Avalanche Application go to Help | Help (F1). Select Contents, Introducing to Avalanche, The Quick Start for Avalanche Appliances (PDF).
The quick start guide provides a summary of the major steps you use to set up and run an HTTP-based test.