how to read data from wwwForm ?

I'm trying to create 1 web server to read the data sent from the client, the client I wrote a function to send
public void sendToService()
{
string url = "http://localhost:64614/api/values";
WWWForm form = new WWWForm();
form.AddField("val1", "value1");
form.AddField ("val2", "value2");
WWW www = new WWW (url, form);
StartCoroutine(WaitForRequest(www));
}
IEnumerator WaitForRequest(WWW www)
{
yield return www;
// check for errors
if (www.error == null)
{
Debug.Log("WWW Ok!: " + www.text);
} else {
Debug.Log("WWW Error: "+ www.error);
}
}
this is my server controler :
public class ValuesController : ApiController
{
[HttpPost]
public string Set(HttpRequestMessage validatedata)
{
//values.val1 = data.val1;
//values.val2 = data.val2;
return "SET DATA : val1 = "+values.val1 + " val2 = " + values.val2 + "data = " + validatedata;
}
}
how to read the data transmitted from the client and stored in the variable on the server, thanks a lot