Extjs Promise with multiple async operations

Have an application where we have to perform multiple async operations (saving 2 stores and save one model) before we execute an callback. So only if all of them are successful we execute some specific code. Of course i could do that with nesting callbacks but still the operations would not be async and (since they are nested) and the code becomes ugly. Saw that Promises are a good solution for this problem. Can someone show me a simple example on how to execute multiple save operations with the help of promises. The reject and resolve is set in the callback function of the model/store save method. But i dont understand the whole picture of when and how i should code such a promise. Thanks for helping