When we want to talk about something that we might do in the future, we can use the words "shall" or "will." Sometimes it's hard to know which one to use, but here's a way to remember:
"Shall" is used when you want to talk about something that you plan or intend to do. For example, if you say, "I shall go to the store," it means you want to go to the store and intend to make it happen.
"Will" is used when you want to describe something that you think is going to happen, or something that you promise to do. For example, if you say, "I will bring you a cookie," it means that you promise to bring a cookie and you plan on doing it.
So, in short, "shall" is about what you want to do, and "will" is about what you plan or promise to do.