Click on TICKETS in the left main menu.

A sub button TEMPLATES will appear under that button click on it now

Select the template you want to edit and click on OPEN

Click on the + icon in the top right corner of the editor menu

Then click on the FIGURE upload icon and choose an image from your files

Then click on the PICTURE icon in the editor menu at the top and drag your picture into the template

Then click on the orange SAVE button at the top right to save your changes