To edit an image click on the image block itself. In the left hand column options for editing the image will display. To choose a different image, click on the Choose Image field.
From the Insert Media window that appears there are some options. You can use the Upload files tab to upload an image from your computer or device. To upload an image from your computer simply click on the “Select Files” button, navigate to the image(s) on your device, select, and upload. Alternatively you can drag and drop the images you want to upload.
If the image you want to use is already uploaded (already exists in the Media Library), select the Media Library tab at the top of the window to browse. From there you can select the image and click the blue Insert Media button in the bottom right corner.
Once the image is inserted, you can make any additional edits using the Image options panel in the left hand sidebar. There you will find options for changing the image size, alignment, adding a caption or link. Additional options for editing the style of the image can be accessed in the Style tab of the sidebar. There you will find options such as, custom height and width, border and box-shadow settings.
Note: editing any type content block is very similar to the above instructions. To edit the content simply click on it and the available options will display in the left hand sidebar.