Follow the below steps.
Step 1: Go to the Registration Template and select the Decorations option.
Step 2: Click on the Layer button
Step 3: Upload the image and set the Image preferences.
Step 4: Click on the Save button. 
Example:
Follow the below steps.
Step 1: Go to the Registration Template and select the Decorations option.
Step 2: Click on the Layer button
Step 3: Upload the image and set the Image preferences.
Step 4: Click on the Save button.