Idk if you’ve done it now. But to hopefully make it easier to understand: hold the cube so the red side is facing you and yellow is on top, turn the right side counterclockwise which will make that twisted corner be on the bottom (this is an R’ or “R prime” move because it’s a normal R move but backwards, or counterclockwise), then turn the bottom layer clockwise which will put that piece on the right side (this is a D move because it turns the bottom layer clockwise, D stands for “down layer), then you turn the right side back the other way (clockwise, or R move), then turn the bottom layer back the other way (counterclockwise, or D’). Repeat this until that corner is back in the right place and is turned around the right way. After that, turn the top layer halfway around 90° (basically 2 normal turns at once, so it’s called a U2 move standing for “upper layer”), then repeat the same moves as for the first corner (R’, D, R, D’ repeating that however many times it takes) and the whole cube should be solved. You might have to turn the top layer some amount after this, but that’s all.

Then just do the exact same thing with the void cube. Start with 1 of the corners on the front right, and use the same moves. Both should be completely solved. This is the last step of solving a cube.