How can I add my logo image to the Thank You notification?

Thank you for contacting us. 

I am not sure if you want to add logo image to Autoresponder or on Thank you page. 

If you want to add image to Autoresponder, than inside of your Autoresponder settings click on Insert/Edit image option and enter URL of your logo image inside of Source field. You can also set dimensions. Same can be done inside of Email Notification as well. 

If you want to add logo image inside of Thank You page, then click on Thank You Page option and select Edit Text. Then click on Insert/Edit image option and enter URL of your logo image inside of Source field. When you are done click on Save Changes.

Hope this will help. Let us know if you need further assistance.