There are two galleries My Images or Image Library where you can upload your own images or use available images from the library.
Upload your own images
Open the tab 'My Images', click on '+ New' and select the right file. The following formats are supported: .jpg, .png, and .gif.
Regarding your uploaded images, you can edit them by clicking on the'pencil icon' and delete them by clicking on the 'garbage can icon'.
Use existing images from the library
Open the tab 'Image Library' and simply select the image you want to use.
Edit the image
It is possible to edit an by cropping your uploaded image and the possibility to resize it as well. Select 'Update' to get the new image, Save a copy to have a new image but still keep the old one or Cancel to discard the Edit.