Let $R$ be $k$-algebra, where $k$ is algebraic closed field. Let $E$ be simple $R$-module. Then, how can I show that $End_{R}(E) \cong k$ ?
I know that Schur's Lemma, stating that "For two simple module $E, F$, Every nonzero homomorphism of $E$ into $F$ is an isomorphism, and $End_{R}(E)$ is a division ring" would be helpful, but don't know how to use this.