what different had,has and have?

we use had for past and has/have for possession

Had is used to show past possession and also in past perfect tense. Ex:- I had a new watch. They had gone. Has/have is used to show present possession and also in present perfect tense. Has- is used with he,she,it,singular subject. Have - is used with I,we,you,they,plural subjects. Ex:- She has eaten. They have new books.