Question about Tutorial - Verify Certificate

Hello everyone, i have a simple question. I am trying to create a verification university certificate system. I can find a lot of github open source projects about that concept but i cant find a complete video tutorial about this. I am trying to understand every signle line of code. A video tutorial i think wanna help me a lot. So do you know a site, youtube video or course with that specific conecpt?

Thank you very much.