Algorithms and flowcharts (Yet another C++ assignment).

If there's one thing I have a hard time with, it's creating algorithms. That isn't the assignment itself, obviously, but if I want to figure out how to write this program, I'll need to figure out the algorithm but the harder I look at the assignment, the more headache it's giving me.

I'm trying to make a flowchart and this is as far as I got.

This is the assignment, by the way.

 Excuse my crappy writing.

I didn't get very far... I need to have the program read the file's inputs and decode what's inside. I'm sure I need while loops for this, and I've no idea when those structs come in. How do I continue?