This is a wonderful question and very common. Keep in mind, it's not just the actual corner of your office, it encompasses the entire area within the wealth section. I created three simple diagrams below to help illustrate where the wealth corner is located based on the Ba-gua Map method of Feng Shui.
To the best of your ability, draw a simple floor plan layout of your office space. In this drawing I did not indicate furniture, just the doorway and the basic shape. I am also focusing on one single room. The arrow indicates the entry point into your office space.
Once you have the basic floor plan layout, separate your office space (eye ball it) to the best of your ability into nine equal boxes. These boxes all relate to the life sections on the Ba-gua map.
Looking to the back left-hand corner, you will locate the wealth life section. This is just step one. The next observation is to review what you have within those parameters as that will help tell a story about the energy circulating within that area of your office.
You may also enjoy: What to do after finding the wealth area of your office - one fast tip