Demonstrate that $1^{2}+2^{2}+3^{2}+cdot cdot cdot +n^{2}=frac{n(n+1)2(n+1)}{6}$

$1^{2}+2^{2}+3^{2}+cdot cdot cdot +n^{2}=frac{n(n+1)2(n+1)}{6}$

Excuse me, I am new to demonstrations. I don’t know how to demonstrate this.. Any help would be very much appreciated! Or tips!

Kind wishes!