If I were you I would write a class that takes a letter say 'A' and writes a big letter to stdout. Obviously you would need to work out how to do it but at least it would be re-usable, so you wouldn't have to write similar code for each letter.
Have a bash at it and see where it takes you. Any problems, then report back here with a snippet of your code and description of the problem you have.
I imagine something like that should cover most upper case letters and numbers (I'm sure you can figure something out if it doesn't), You'd still need to create a derived/instance for each letter but at least there's less work in doing this.
In order to handle an string you've got several options
1. maintain a matrix that represents your display. Write all the letters there, then print the matrix.
a. move the cursor with `gotoxy()' functions, you'll need to use a library like ncurses.
\alpha. work as with scanlines. Traverse the string and print the top line of each letter, then the second line of each letter, and so on.
> From the document the OP included as a link
It was a *.docx. There wasn't a good reason to use such format.
The example input/output would be better seen as text than an image (I understand that that may not be your fault, complain for me)