I can't understand where I use do did or I use exurli verb like is are

Hi! First, you have to understand which time are you using. Present time Affirmative I sing I am happy With negatives and interrogative forms remember you need an auxiliary Do\Does when you do NOT TALK with the verb TO BE (am, is, are)... I do not sing ( Verb SING with auxiliary) Do I sing? I am not happy ( Verb TO BE no need aux.) Am I happy? DID- is the auxiliary in past times I did not sing Did I sing? If you think about verbs with the verb TO BE, you think about "continuous tenses". Example: The main verb is Sing I am singing/ She is singing / They are singing Present continuous

I am happy