The map $\left(\frac{.}{p}\right):=\mathbb F_p \rightarrow [\pm1]$ taking $a\in \mathbb F_p$ to $\left(\frac{a}{p}\right)$ is homomorphism

Question

Prove that the map $\left(\frac{.}{p}\right):=\mathbb F_p \rightarrow [\pm1]$ taking $a\in \mathbb F_p$ to $\left(\frac{a}{p}\right)$ is a homomorphism

I don't know how to even start this problem. I would greatly appreciate it if someone could help me.