Seeing the dreaded Request Error page while testing your WCF Web Service?

Well, worry not, because this StackOverflow answer shows you how to turn on detailed error display: WCF Data Service - How To Diagnose Request Error?
But ... hang on, we don't have a Web.Config that looks anything like that one.
Ours just has a system.serviceModel and that's it.
<system.serviceModel>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true"></serviceHostingEnvironment>
    <standardEndpoints>
        <webHttpEndpoint>
            <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true"></standardEndpoint>
        </webHttpEndpoint>
    </standardEndpoints>
</system.serviceModel>
If we go for it and simply add the following:
<behaviors>
    <serviceBehaviors>
        <behavior name="DataServiceBehavior">
            <serviceDebug includeExceptionDetailInFaults="true"/>
        </behavior>
    </serviceBehaviors>
</behaviors>
on to the end, then boy is it unhappy:

Update/Edit
Based on answers and comments from @burning_LEGION and @Chris (see below) I now have a Web.Config which looks like this:
  <system.serviceModel>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true"></serviceHostingEnvironment>
      <standardEndpoints>
    <webHttpEndpoint>
          <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true" behaviorConfiguration="DataServiceBehavior"></standardEndpoint>
    </webHttpEndpoint>
      </standardEndpoints>
      <behaviors>
    <serviceBehaviors>
      <behavior name="DataServiceBehavior">
        <serviceDebug includeExceptionDetailInFaults="true"/>
      </behavior>
    </serviceBehaviors>
      </behaviors>
  </system.serviceModel>
But I'm getting a Server Error:
Parser Error Message: Unrecognized attribute 'behaviorConfiguration'. Note that attribute names are case-sensitive.
 
     
    