Needle felting involves knitting fibres together using a serrated needle. The motion of stabbing the needle up and down tangles the fibres together and the shafts on the wool interlock to make the fibres into something more solid.
I’ve tried needle felting a few times, and like any craft it takes practice - I’m still not very good at avoiding stabbing my fingers at the same time as the wool! As Im still a novice, the needle felting projects I’ve tried have been from kits. If you are more experienced needle felter you can source the wool roving and other materials yourself and create your own robin design.
For all the materials and full instructions this is the kit I used to make the robin.