Click Image from File and browse to add image. Click any image to select - drag to position - mouse-wheel to re-size. SHIFT + ◄ or ► to edit opacity. Click Set Image as Background to lock selected image as background. Check Repeat Background to tile image over Clock Face.

Enter text and click Add Text to add to Clock Face. Click any text block to select - Drag to position - mouse-wheel re-size - Colour and Font. You can also re-size Text and Images with either your Mouse Wheel or SHIFT + ▲ or ▼
Use SHIFT + < and > to Rotate Text.

Select a background theme and click Get Backgrounds to search on Google Images for free backgrounds. Open the page with the background image, right click the image and choose 'Save image as...' to save the image to your computer. Now click Select Image, browse to the saved image to load, drag to position and resize with mouse-wheel.

Click Set Image as Background (make sure image is selected by clicking it) to lock and crop the image as a background.