How do I post adaptive payment information to paypal?

I've managed to get an adaptive payments script to work in the apigee console, here is the request:

X-PAYPAL-REQUEST-DATA-FORMAT: JSON
X-PAYPAL-APPLICATION-ID: APP-80W284485P519543T
X-HostCommonName: svcs.sandbox.paypal.com
Host: svcs.sandbox.paypal.com
Content-Length: 428
X-PAYPAL-DEVICE-IPADDRESS: 127.0.0.1
X-Forwarded-For: 10.203.10.109
X-PAYPAL-REQUEST-SOURCE: APIGEE-CONSO开发者_JAVA技巧LE-1.0
X-Target-URI: https://svcs.sandbox.paypal.com
X-PAYPAL-RESPONSE-DATA-FORMAT: JSON
Content-Type: text/plain; charset=ISO-8859-1
Connection: Keep-Alive

"{
  "actionType":"PAY",
  "currencyCode":"USD",
  "receiverList":{"receiver":[{"amount":"5.00","email":"cam_1315509411_per@btinternet.com"}]},
  "returnUrl":"http://apigee.com/console/-1/handlePaypalReturn",
  "senderEmail":"qwom_1315508825_biz@btinternet.com",
  "feesPayer":"SENDER",
  "cancelUrl":"http://apigee.com/console/-1/handlePaypalCancel?",
  "requestEnvelope":{"errorLanguage":"en_US", "detailLevel":"ReturnAll"}
}"

How do I actually post this information to the https://svcs.sandbox.paypal.com/AdaptivePayments/Pay url? I can't find the easiest way to do it, should I use cURL and what are the variables names for each post value?

That depends on the rest of your application. PHP with cURL is fairly straightforward, but it's not too much of a hassle in other languages either.
PayPal has sample code online at https://www.x.com/developers/PayPal/documentation-tools/code-sample/78

If you were to do this yourself, you'd need to (in a nutshell):
- Send a proper HTTP header with the X- headers as shown above including the application ID.
- Send the API call via JSON, SOAP or NVP as POST or GET to the API endpoint
- Decode the response and act accordingly