A sentence that tells us something is a statement. A statement can be changed into a question by using do, does or did as the first word.
He likes writing stories. (Statement)
Does he like writing stories? (Question)
She loves little children. (Statement)
Does she love little children? (Question)
They visited us yesterday. (Statement)
Did they visit us yesterday? (Question)
Notes: Some statements will have auxiliary verbs in them. One way they can be changed into questions is to put the auxiliary verb first.
She is fond of children. (Statement)
Is she fond of children? (Question)
They are waiting for you.
Are they waiting for you?