@yukinoh1989 Hi Yukino, using HDRI in EEVEE works the same as in Cycles. I think Aaron explained it in the previous class how it works. Else you can watch the fundamentals of lighting course, there Kent explained it too.
Best place to get them for free: HDRI Haven
Can’t really see the shaders… I think you’re only using the standard grayish world lighting. Adding a sun lamp will help 🙂