When I did connection from Windows to PostgreSQL using ODBC, I used DSN-less approach. It requires zero input from user perspective - user does not need to know what ODBC is and how to configure ODBC source (DSN).
Typical way to use DSN-less connection is to use string like below as your ODBC connection string:
Driver=PostgreSQL;Server=hostname;Database=mypgdb;UID=username;PWD=password
Note that driver name may need to be adjusted depending on version and ANSI vs Unicode flavors.