Using the Image Editor - New Editor
To add an image to your email, make sure a content block that contains an image is included in the body of your email. Once it is, simply click on the gray image icon to upload your own image. When you do this, the Image Editor will appear.
Hover over the gray image icon and click "Change Image" to upload your own image.
Once you've uploaded an image, you can use the slider bar to resize it. You may also type in a specific height or width for the image in pixels. The Image Editor will always respect the aspect ratio of the image, so that images do not appear distorted.
"Description" is the ALT text for your image. Give a brief description for your image. This is the text that people will see if their email browser has not yet downloaded the images in your email.
"Link to" allows you to link the entire image to either an email address or a website.
Next: Image Map, Step 4.