To embed images in contracts, the first step is to add placeholders for these images in your Team's template(s). Note that only Team Editors or Owners have access to the template editor, where these placeholders are created.
Image placeholders are added to templates as a variable type called an image variable. Create image variables by clicking the "new variable" icon at top center of the screen:
Format the new variable as an image by choose "Image" from the drop down list:
Choosing "Image" creates a placeholder in the template where an image (.PNG or .JPG file type) will appear in all new contracts.
If the embedded image will always be the same, upload this image in the template while creating the variable. From them on, this specific image will show up in contracts created from this template.
If the image will change from contract to contract, you may leave the placeholder empty in the template, to be filled in during contract set up. Click on the image variable during contract review to add or replace a picture displayed there: