To insert a form in a message you can use Special Links. Here is how to do it:

Create a new email message

If you're using the drag and drop editor, you can link the form to a button, by selecting it and choosing Special Links in the "Action" section of "Content Properties".

You may also link a profile update form to a portion of the text, by highlighting it, toggling the advanced toolbar with the arrow in the top right and selecting Special links > Profile update forms

1. If you're using the HTML editor, you can link a part of the message to a profile update form using the "Profile Update link" found in Insert > Subscription
Finalize and save the email message
Send it to a test group to simulate the entire process
When you get the test email, fill out the form and submit it
Confirm that the Recipient Fields associated with the recipient that updated the form have been successfully updated