This colour chart explains how colours work and how they can work together in harmony.

You have your PRIMARY colours of RED, YELLOW and BLUE

You then have your SECONDARY colours ( two primary colours mixed) of ORANGE, 

GREEN and PURPLE

Your tertiary colours (mixing 1 primary with one secondary, or two secondary colours) are your colours in-between like bluey greens etc

This wheel also explains your warm and cool colours. 

Now lets explain in detail:

 The WARM colours in the chart are welcoming, they are advancing and appear to approach you in a photograph. COOL colours in the chart above create a variety of emotions but the one thing they have in common is that they are receding, they mainly play a background role. They work beautifully in the background of an image and together with warm colours can help the WARMER colour advance even more!! Orange and blue is a good example of warm and cool working together as these are also COMPLIMENTARY colours too. Complimentary colours are colours that are opposite to each other on the colour wheel. A great example would be red and green, as its coming up to Christmas I thought it to be quite apt.

Your warm colours  RED ORANGE and YELLOW create feeling of energy, cool colours such as GREEN, BLUE and PURPLE are said to be calming.

Yellow and blue is another good example: Thats why road signs look so effective, the sign represents a strong energetic object while the background of the blue sky creates a calmness and recedes, helping the advancing yellow sign come towards the viewer.