Hi Ceremona, welcome to the forum!
If you look at the '?' there is a full blown user help for how to utilise these sources.

As can be read, the url you need to post to is http://[mangodomain|localhost]/httpds
Anyway, you see that set point url I'm pointing to?
EDIT: Sorry I meant to mean device white list, I was pointing at the wrong textbox!
You set that as your reference so it will land (the data) in this datasource.
the parameter being __device
Here's a snippet:
var _URL="http://ipAddressHere/httpds?__device=DEMO&QUANTUMM1="+pt*.value+'@'+pt*.time;
httpReq(_URL,"post",res,{'Content-Type':'application/x-www-form-urlencoded'},{});
Where in this case QUANTUMM1 is my point identifier in the data point in the data source itself.

The format as you can see in the code (1 of the allowed formats at least, read the datasource help for the others) is "+pt*.value+'@'+pt*.time
So value first, separated by an '@' then a timestamp. NOTE This format I believe is the publisher set format for the set format option of this datasource so you can use a mango publisher to flick data via an http publisher to a mango http receiver datasource.
So as a recap:
params: __device=[setPointUrl]
&httpParameterName=[value]@[Timestamp]
url: mangoUrl/httpds
You can test by clicking on the 'Listen for HTTP data' button to ascertain if your values are coming through.
Any further confusion, we're all here to help
Fox