Ignoring the cross
R2 D'
Or turn the green face 180 degrees then turn the white face anti clockwise.
Assuming your cross is complete, L U L' will pair the edge with the corner, and then R U2 R' will put then both in place. The reason it looks like the corner is flipped is because the white and yellow stickers don't match.
Regarding the remembering and revealing algorithms thing. It's a lot easier than you think. Think of all the things you already remember. How many people do you know? How do you see a person's face and you immediately know their name? And how many objects can you name? I don't understand how memory works, but it's amazing. Adding just a few dozen OLL and PLL cases to that massive list is tiny. In terms of remembering the moves, it all goes into muscle memory. It's like a musician who goes up on stage and plays a piece on an instrument. The music is remained in their muscle memory from hours of practice. Learning algorithms is like that, just much much easier since algorithms are much shorter than your average piece of music.
I think you need to step back from tutorials for a while and try working with the cube on your own. Think about how the pieces move, and try to see if you can figure out your own way of doing steps.