To create an email signature with an image, you will first need to upload the image to a 3rd party host in order to obtain the image URL. Once you have the image URL, you can then paste this into the signature in Zenu.
You can use a third party such as Dropbox to generate this URL.
Once you have saved your image to Dropbox, right-click on the image and click COPY IMAGE ADDRESS. This will copy the URL for the image.
Navigate to Email Signature templates, in the edit field, click on the Image icon and paste in the image URL.
You can refer to the width and height fields to adjust the image sizing.