When I add my dad as a user on plex pass how does he view my tv shows and movies on his computer?

When I add my dad as a user on plex pass on my plex media server how does he view my tv shows and movies on his computer?

Have you shared your libraries with him?
This guide should help you:
https://support.plex.tv/hc/en-us/articles/201105738-Create-a-New-Share

Does your dad live close to you (i.e. in the same house) or further away?
If it is the latter, I recommend he makes a free plex.tv account for himself.
You then share your server with this new account of his.

He just needs to start a web browser on his computer and go to plex.tv. Log into his account and press ‘Launch’ (top right corner on the web site).

If he later wants to use a Plex app which is not free (but free with Plex Pass), you can invite his user account into your Plex Home. But this is a separate procedure and can be performed later.

Before you get him to make an account, do verify that you can access your server when away from home.
https://support.plex.tv/hc/en-us/articles/200484543-Enabling-Remote-Access-for-a-Server