The Input File contains the data supplied to your program and is displayed in the same format as you would see if you had used the unix cat command.
Your program receives the input the same way as if you had issued the command :-
awk -f program_name Input File
With the program_name being the code you write in the programming window situated below the Input File.
Your program should use the standard method for accessing the input file. For example, referencing the variable $1 would access field one, etc.