I drool over a proof of a theorem called the correspondence theorem. That's the issue :
Let $A$ be a ring and let $I$ be an ideal of $A$. Then there exists a bijection between the set of ideals of $A$ containing $I$ and the set of ideals of $A / I$ . $i.e$ : There exists a bijection $\lambda : \{ J \,/\, J\,$ ideal $\,of\,A\,; I \subset J \} \to \{K\, / \,K\,$ ideal $\, of\,A/I \}$
Can someone please explain me how to define such a bijection. And thank you in advance.