One of the advanced features available to paid subscribers is the ability to store documents in your account’s GeniusDrive to add as attachments on sign ups or in emails sent from the account.
To attach files to a sign up, log into your account and click "Tools" on the left side of your account Sign Ups page. Choose "GeniusDrive" and upload your document(s). You can then go back to your account Sign Ups page and click on the pencil icon to the right of the sign up for which you want to attach that document. You’ll find the option to “Attach Files” under the Advanced Settings near the bottom of the page.
You can also include the document as an attachment to an email when using the "Messages" area of the account to send emails.