How do i make unlockables for my obby?

Okay so i am just wondering if anyone here knows how to make unlockables for obbys for example i have a game called checkpoint world with 5 modes standard, Hardcore, Perfect, Timed and Demonic and i want to make a GUI pop up once a player has beaten any of the modes giving them the unlockables from beating the obby in any mode if you know how to do this then please do consider helping me out with this