Select the style of widget you'd like to use, and choose Edit Widget.
Select the light, coloured, or dark background; then select colour theme, font, and background photo (either what they provide or your own photo).
Select Set Widget. This will now show up at the top as Active Widget. You can tap on it and choose between 12hr Time or 24hr Time and Show Battery or Hide Battery.
Exit app.
Hold down your finger anywhere on your screen (or on an app and select "Edit Home Screen") until the apps wiggle.
Tap the + icon in the top left corner.
Search and select Colour Widgets, pick the size you want to use, and tap Add Widget to add it to your home screen.
Move your widget to the location you want on the home screen and then select Done in the top right corner to set it in place.