Net.WebService and .Post for json REST request

[HGexperimenter]

Help for a newbie:
Has anyone built a program that uses Net.WebService and .Post for a json REST request?

Here is a cURL request that works: (note the escape characters for \")
curl -d "{\"tmode\":2,\"t_cool\":80}" http://<url>/tstat

Here is what I tried in HG (does not work):
string postString = "{\"tmode\":2,\"t_cool\":80}";
var resultPost = Net.WebService("<url>/tstat").Post(postString);

It does not change the thermostat and does not produce an error.
The <url> is OK because I can do a .GetData()

Thank

[HGexperimenter]

OK - figured it out

       var postRequest = Net.WebService("<url>/tstat")
         .AddHeader("Content-type", "application/json")
         .Post(postString);
       var postResult = postRequest.GetData();

It needs the GetData() to finally send (or Call) and get the result.