In Web API the URL can be configured by yourself by means of the urlmappings that you will find by default in the App_Start folder. If you use Visual Studio to generate a WebApi controller from EF, by default the url will match your root folder followed
by the name of the controller.
Since you asked in the Training and Certification folder, this is taught in courses 20486 and 20487. If you need further help about the web api itself (and not about the training courses and certifications that deal with it), then you should ask about it
in one of the technical forums, such as this one:
http://forums.asp.net/1246.aspx/1?Web+API instead of the Training and Certification forum.