For Grubb, to unlock Jim Ryan all you have to do is download the PlayStaion app on your phone and enable PS stars in there. In the app you'll get a quest to boot one game from a list. Boot the game and after a few seconds you'll earn the reward in app. You can add earned awards to a display shelf in the app. As far as I know there is no way to share this outside of the app except by taking a picture directly on your phone.
The actual use for PS Stars is similar to the MyNintendo Rewards gold coins where you earn points for purchases to get discount coupons. There are some bonus points given each month for booting the PS Plus essential monthly game and/or buying/booting games released that month.
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