Insert form items from the menu when editing the page, put the name of the item in the "name" field of the form item, and the value of that item as the "value" or the form item.

Name and email fields are compulsory for payment, if you want to collect that information here just name the fields fname, lname and emailaddr. The system will recognise those fields and won't ask during payment.

Click edit and remove this text to get started.