Take your material and start playing - it's easy and fun!
Start with any piece of watercolour paper and use clean water to wet it with your brush. Check the wetness of the paper by turning it and looking at it from the border : it should be damp all over, without pools!
Now choose 2 or 3 colours and start dropping colours onto the paper! You can mix some colours, if you want, or just let them mix on the paper.
Let the colours spread and see how beautiful the result is without any effort! This is the basics of wet-in-wet painting and You will enjoy playing like this even if you are a more experienced painter!
This is Wet in wet - It's easy!