You use shall with 'I' and 'we' in questions in order to make offers or suggestions, or to ask for advice.
Shall I get the keys?
我去拿钥匙好吗?
Well, shall we go?
那,我们走好吗?
Let's have a nice little stroll, shall we?
咱们去好好散散步,好吗?
You use shall, usually with 'I' and 'we', when you are referring to something that you intend to do, or when you are referring to something that you are sure will happen to you in the future.
We shall be landing in Paris in sixteen minutes, exactly on time.
我们将于16分钟后准时在巴黎降落。
I shall know more next month, I hope.
我希望下个月能知道更多信息。
You use shall with 'I' or 'we' during a speech or piece of writing to say what you are going to discuss or explain later.
In Chapter 3, I shall describe some of the documentation that I gathered.
在第3章,我将讲述我所搜集到的一些文献资料。
You use shall to indicate that something must happen, usually because of a rule or law. You use shall not to indicate that something must not happen.
The president shall hold office for five years.
总统将任职5年。
You use shall, usually with 'you', when you are telling someone that they will be able to do or have something they want.
Very well, if you want to go, go you shall.
很好,如果你想走的话,你可以走了。