In Wikipedia, on the page on del Pezzo surfaces, it is written that
The only degree $9$ del Pezzo surface is $\mathbb{P}^2$. Its anticanonical embedding is the degree $3$ Veronese embedding into $\mathbb{P}^9$ using the linear system of cubics.
The only thing that is clear to me here is why there is a degree $3$ embedding in $\mathbb{P}^9$, since we consider monomials of degree $3$ in coordinates $x,y,z$, of which there are a total of ten of them, each corresponding to a coordinate in $\mathbb{P}^9$.
However, how do we see that this is the anticanonical embedding?