How can I find about my father’s deployment in Vietnam?????

Best place to start is the National Archives. As the child of a veteran you can request military service records. You do need some information to start this process, but it is a free service.

This article also has some useful tips and resources.

If you currently know your father’s unit, I strongly suggest googling it because many veterans have established websites to meet other veterans they served with and to document their service. They often post pictures.