In addition, Shall is used to show how ready you are to help or to do something. for example, when you see an eldry person carrying items, it'd be kind of you to say ''shall I help'' meaning i'm going to carry them for you right now while ''can I help'' means you are waiting for a response.

It is used in future tense. You can use it only with first person - I shall do, we shall do. But now people mostly use "will" instead of "shall".