To put a signature on a Palm Treo, first, tap the "Email" application icon and then tap the "Email" button. Then, select "Preferences and Accounts" and then select the e-mail account where you want to add the signature. Next, select the "Signature" heading in your email account settings. After that, tap the "Signature" text box and type in the signature. For more information, visit http://www.ehow.com/how_8455574_put-signature-palm-phone.html.