This is the last step of the 'Beginner's Method.' In this step you will learn how to orient the remaining corners in the top layer. This is by far the algorithm that will be tricky and difficult to understand.
Learn this tricky Algorithm
Algorithm: R' D' R D
What is does is orient the corner, note that it will disrupt the other pieces around the cube. As long as the yellow corner is facing up you will be fine.
YOUR GOAL
Begin by looking at any corner around the top layer.
If the corner is facing to you, perform the algorithm 4 times. If the yellow facing up stop. Then do a U to do other corner pieces.
If the corner is facing to the side, perform the algorithm 2 times. If the yellow facing up stop. Then do a U to do other corner pieces.
The Cube should be solved!
If you know the Beginner's Method by heart, I would recommend looking at this.