Paypal express checkout integration

This is for paypal express checkout integration: I need to post data to the PayPal API server and read the return variables. I can do it with a form where I set the form's action url to the Paypal API server and post data using (hidden) form fields. But the problem is that this takes me to the Paypal API server where I can see the return variables on screen but there is no auomatic way back from there to my site. So what i need is to post data to Paypal without the form. Pass an array of variables and capture the return variables. Important: This is an HTTPS post not HTTP (I know how to do HTTP) so please only bid if you can do this for HTTPS as the Paypal API processor sits on HTTPS.