The top of this window has a series of tabs for different keyboard shortcuts, such as Control and Apple or Shift and Apple. There will be a depiction of a keyboard for you to view. Go ahead and click on the command you are trying to assume and either drag it onto one of the preset tabs, with keyboard combinations like Control and F, or onto one in the keyboard to assign it. You can work with this menu as much as you like until you feel satisfied with the new keyboard set-up. From here you can go ahead and set the changes as the new shortcuts and they will appear as such until you change back to the default or alter them further.