Assalamoelaikoem warahmatullahi wbarakatuh,
First of all it's important for a person to have firm believe in God. If he has doubts about he Existence of the Creator, you can start with convincing him.
Q: How can you do that?
A: Show him some verses from the Quran which talks about the Creator and the Creations.
When he firmly believes in Allah, you can inform him about the messenger of Allah, Muhammad Peace be upon him and islam and the prayers in islam etc...
in summary: You start with the information about Allah, in islam it's called tawheed. Afterwards you give information about our prophet and his message which is islam.
Do you have more Questions, please don't hesitate to post them.
I have a question: Does your father have an email-adres?
Thanks
Wassalamoelaikoek warahmatullahi wbarakatuh