The Email Editor lets you edit your images once they've been uploaded to the File Manager.
See this article for how to upload an image: How do I upload an image to the Email Editor?
Once you've chosen an image and placed it in your Email Template, click it to select and choose the "Apply effects & more" button to bring up the image editing options:
The image editing options include the ability to re-size and crop as well as various visual effects to customize the appearance of your image:
Once you've made the edits to your image, press the Save button to save your changes and return to editing your email template.
If further assistance is required, submit a ticket to Punchh Support. (For help submitting a ticket, click here)