How create a WADL for Data Services (RestFul)?

Hi

Which are the steps to create a WADL for Data Services 4.2

or

What should be the structure of the WADL?

or

Which are the steps to import a WADL?

I am using SopUI to create a WADL from a url, but when I import the function  to a Datastore (rest), I get a empty function or xml error.