PSR473 - Importing

[Daparojo]

I have purchased a Yamaha PSR473 which I am finding to be really good to enhance my basic keyboard skills.
I am really intrigued on how to create something like these on these clips ?

The rhythm and the one finger sound on left hand at the beginning oghthe clip?
https://www.youtube.com/watch?v=E0nrd5blnOQ

How do you import a rhythm like this ?
https://www.youtube.com/watch?v=MbFujv6UJxA

Any guidance would be helpful