Could you tell me 后面应该加疑问句还是陈述句

Could you please tell me (where the library is)?

后面需要跟宾语从句，而宾语从句的语序是跟肯定句一样的。

Tell me 后面加的是陈述句还是疑问句
例如Tell me how can I do it?还是Tell me how I can do it?
Tell me 后可以接由陈述句和疑问句变过来的名词性从句
如：
Tell me that you are wasting your valuable time.(接陈述句变过来的宾语从句）
Tell me whether he is there..(接一般问句变过来的宾语从句）
Tell me where you have been..(接特殊问句变过来的宾语从句）
Tell me how I can do it 是对的,因为how I can do it 已经变为名词性从句了,不再是独立的疑问句了,所以不能倒装

Could you tell me your name?
作肯定回答·否定回答·改陈述句和一般疑问句和否定句。
肯定回答：Yes, of course..
否定回答：Sorry,I'm afraid not.
陈述句：I'd like to know your name.
一般疑问句：What's your name, please?