Specifically, for console applications, main() is defined as the entry-point to the application (where execution begins), and when execution reaches the end of main() execution then ends. In the code you posted, this is the entirety of what actually happens
when your application is run:
1. Execution begins at the entry point, main(), defined as:
2. Main immediately returns 0, as it says, ending the main() function.
3. Execution terminates, as it has reached the end of the main() function. No other functions are called nor run.
In order for other code to be run you need to call other functions from inside main() or do something else which passes execution to elsewhere in the code, which you never do.
Some other problems I see:
float Score1, Score2, Score3, Score4, Score5;
float highestScore = Score1;
The definition of highestScore makes no sense, because at that point Score1 has no definition. You are assigning highestScore to something completely undefined. You should just leave it undefined in that definition, and assign highestScore to something after the other variables actually have a definition of their own. On top of that, using global variables (Variables which are defined outside of functions, classes or namespaces) is generally a very bad practice. You should make a habit of defining them inside the function, class or namespace ("scope") where they are relevant.
Some of your fundamental understandings of the language were flawed when you wrote this, although not horribly so. I'd recommend doing a little bit more reading on the basics and then giving it another shot.
edit: If you're going to just say "No I'm not wrong I'm right!" when asking for help, I'd recommend you not bother asking in the first place.