You can enter text into the tooltip field on the accessibility palette and when th euser hovers over the field that text will pop up. This isi good is you have a small amount of text. For something bigger you can put a button beside the field witha question mark on it. When th euser clicks this button you could put up a message that woudl have the extra help for tha field. The command to bring up a message is xfa.host.messageBox("Enter your message here")
Paul