I really want to get married but I don't know how to tell my dad and I need to tell him why I want to get married but I don't know what to say or how to start

You need to sit down and have a very long honest talk about your plans with your father and what you would like to do.

Why is it that you feel you can not shear this with your father ?

People get married because they love each other. Is there a different reason that you want to get married?

First is, do u love her,
If so, then just tell him your feelings and believe he will surport you...
Richard