To get started with REST testing, you'll first want to create a New Test Group, and then add a new REST test case.
With your new REST test case, as you complete the fields the URI will be built for you.
For instance, you enter values for the Host and Path fields, and then add your URI parameters in Name=Value pairs.
Lastly, you can change the HTTP Method used.
Use the "green circle with white check mark" to commit your settings and then the "blue circle with the white arrow" to send the request to the service.
To view and add custom HTTP Headers, click the Headers icon.
To add SSL or HTTP Authentications, click the Authentication tab at the bottom of the Request window.
To add Task processing, click the Tasks tab at the bottom of the Request window.
With REST test cases, just as with SOAP and XML test cases, you can parameterize your inputs, the URL, query string parameters, etc.. using the context functions, runtime variables, data source variables, etc.