Navigate to the Menu and click on Site Settings.
Click on the Themes option.
Click on Create New Theme.
Give the Theme a name.
Choose Pathway Theme from the dropdown list.
Click on the Create button within the popup window.
You will be taken to the Edit Theme area where you will be able to start editing your Theme. 
This area allows you to edit the Pathway's title, tile and text colour along with the ability to upload your own image to use as the Pathway's background.
Change a colour
Click on one of the colours to amend it and a colour picker will be displayed.
Simply move the slider on the right-hand side to find the colour you'd like to use...
..and click onto a colour within the colour wheel to select it.
Alternatively, type the hex code for the colour into the box.
Click on Choose to select the new colour.
Upload an image
Images can be uploaded wherever you see the Upload button:
Navigate to the file on your computer and open it to add it to the Theme.
The recommended image size is 960 pixels wide x 550 pixels high and can be saved in jpg or png format.
Tick the Display preview on transparent background box to preview what the image will look like once it has been added to the page.
Save your changes
When you are happy with your Theme, click on the Save button at the bottom of the screen to save the changes.