If you aren't sure what a method does, the first thing to do is turn to Google: "Console.read"
This normally finds the MSDN at the top of the list: MSDN: "Console.Read Method"
] which generally explains it pretty well.
In this case, Console.Read returns a single character the user typed: '1' in an integer - which has the value 49 in decimal. Your write method (when handed an integer) writes that integer as a string to the file: "49".
Perhaps you want to consider using Console.ReadLine instead? That would return "1234" as a string instead.