Helping verbs or auxiliary verbs such as will, shall, may, might, can, could, must, ought to, should, would, used to, need are used in conjunction with main verbs to express shades of time and mood. The combination of helping verbs with main verbs creates what are called verb phrases or verb strings.
DO, BE and HAVE are the English auxiliary verbs used in a negative structure, a question or to show tense.
DO, DON'T, DOES and DOESN'T are used for questions and negatives in the Present Simple Tense. From Auxiliary Verbs to HOME PAGE
DID and DIDN'T are used in the Past Simple Tense.
BE is used with the Present Participle in Continuous (Progressive) Verbs. It is also used with the Past Participle in the Passive.
HAVE is used with the Past Participle to form the Perfect Aspect.