To define the properties of a button, you must first select the button. Set data-submit properties in the Submit tab of the Object palette. To view the Submit tab, you must select the Submit option in the Control Type area in the Field tab.
You can specify the format and type of data to submit, and the type of data-encoding. If the button submits the data in URL-encoded format, you can specify a URL to post the data to. If the button submits an XDP file, you can include attachments, such as annotations, PDF documents, or signatures. You can also apply a digital signature to the submitted data.
See also 

About submitting data using a button