There are a number of ways to find a postdoc position. Some positions are advertised on the Cornell website at http://hr.cornell.edu/jobs/index.html.
Most often, postdocs positions are found by networking and contacting faculty directly. A list of all departments at Cornell can be found at: http://www.cornell.edu/academics/departments.cfm
Postdocs are hired directly by the faculty and department with whom they will be working.