How can send Email attachments through code with API wt.mail.EMailMessage.addAttachments ?

wt.mail.EMailMessage message = wt.mail.EMailMessage.newEMailMessage();

message.setSubject("Mail Subject");

message.addRecipient(user,1);     //recipients paramInt = 1

message.addRecipient(boss,2); //ccRecipients paramInt = 2

message.addAttachments(??????); //Help Me

message.setOriginator((WTPrincipal)wtsender);

message.addPart("Mail Content","text/html");

message.send(true);