Which colours can I use and what does this mean?

You can use colour or black and white photos. The colours you can see on your screen are low resolution and therefore vary slightly from the printed version. Please note that we print in CMYK, a colour printing process using the colours, Cyan (blue), Magenta (lilac), Yellow and Black, in which the colour is produced from a mixture of these four colours. Make sure you save your photo as CMYK in your editing programme. If you use pantone colours your photo will only print in an approximation of the chosen colours.