Use the open function to open the file. The open function returns a file object, which you can use the read and write to files:
file_input = open('input.txt') #opens a file in reading mode
file_output = open('output.txt') #opens a file in writing mode
data = file_input.read(1024) #read 1024 bytes from the input file
file_output.write(data) #write the data to the output file
