The Western Union Scholarship is a single $1,000 payment funded by Western Union and given to one incoming international student at the University of Wisconsin-Madison each year.
To qualify you need an F-1 or J-1 visa to study at UW-Madison, citizenship of a country that is underrepresented in the current international student body, admission for an autumn term, and you must be starting your first undergraduate degree. The university does not publish which countries count as underrepresented, so ask the admissions office if your own case is unclear.
There is nothing extra to submit. The admissions team nominates candidates from the admission application itself, and the single recipient is then picked at random and told by email. Treat it as a small bonus on top of whatever else funds your place, since $1,000 covers a fraction of a year at Wisconsin.