Group structure on $[X, \Omega^{2}(Y)]$ is abelian

Question

I'm very begginer when it comes to algebraic topology. I have no idea how to prove (firstly see why it could be true or even start) this statement:
Composition of loops gives the structure of group on $[X,\Omega(Y)]$ (Yes, I see this). We define $\Omega^{2}(Y)=\Omega(\Omega(Y))$. Prove that group structure on $[X,\Omega^{2}(Y)]$ is abelian.
I would be thankful for help.