Paypal Express Checkout Complete Reference

Paypal documentation provides a complete how to do for Express checkout operation:

This link shows how to do it using forms(Manual submission for every step)

https://developer.paypal.com/webapps/developer/docs/classic/express-checkout/integration-guide/ECGettingStarted/

The same can be done by using API call directly.
In PHP this can be done with help of CURL.

Paypal Express Checkout - to show order details

Paypal Express checkout;

Item Description not displaying in the paypal problem

Express Checkout does not show order details by default, because your website is supposed to do this before and after your buyers are directed to PayPal.

https://www.paypal.com/cgi-bin/webscr?cmd=_express-checkout&useraction=commit&token=[token returned in the SetEC response]