There is no option to watermark images on the Colour In Your Life website. While the site does have systems in place to prevent the copying of images where possible, there will always be individuals that try to subvert the system.
If you wish to protect the copyright of your work, please look at adding watermark images/words to your work. A watermark can be text, an image, or a copyright symbol.
Ideal programs include Photoshop, and those listed below:
The Digimarc for Images software can watermark your photos invisibly and then search for places where your photos are being used on the Internet for $49 per year.
For about $20, you can download a Windows version of the iWatermark watermarking software from PlumAmazing.com. The site also has Mac, iPhone/iPad, and (soon) Android versions of the software.
AiS Watermark Pictures Protector also costs about $20 and can be downloaded from Watermarker.com.
With the WinWatermark software, you'll find many options for watermarking your photos. There's a free version, a standard version ($30) and a pro version ($50) at WinWatermark.com.