She also has tons of other advice videos that can answer your other questions beyond your question about how to plot. Also I realized I wanted to add more from my own experience about trying to become a writer in addition to what I said above.
What you said sounds exactly like me several years ago when I first started seriously trying to write. And I felt like a sucked so bad (and I did lol). It felt like I had no idea how a story should go, either, even though I read so many books! What really really helped me was to take a step back from trying to write for a little (although @FallenSinAza 's advice about just practicing writing with short stories is great too for when you're ready to sharpen your writing skills) and try to just think and learn about writing. I researched a lot of stuff online, and that was helpful to an extent, but there's a lot of bad advice along with the good advice I've found lol. The thing that helped me the most was to think about my favorite books, movies, and stories in general and then try to pick them apart and answer WHAT exactly I liked about them and WHY. That was mind blowing for me. As I got more used to dissecting my favorite stories, I could start breaking down my favorite characters, my favorite plot points, my favorite worlds, etc. Eventually I started to see patterns emerge in my preferences and after that I started to come up with ways for how to execute myself the things I liked in other stories.
Ultimately, you should be writing what you would love to read, so go find the things you love and dissect them!