Sagot :
Have is used to refer to a plural subject while in addition to that, Has is for singular. Has and Have are used in the PRESENT TENSE OF THE VERB, especially in the Present Perfect and Present Perfect progressive form while Had is used for PAST TENSE OF THE VERB :)
Have is use when your sentence is in present form while had is in past form.
Example:
Have
I have a meeting right now.
Had
We had a meeting today.
Example:
Have
I have a meeting right now.
Had
We had a meeting today.