Long but please HELP

I'M TRYING TO WRITE A PROGRAM BUT AM COMPLETELY LOST AND DON'T KNOW WHERE TO START W/ MAIN. IT'S A PROGRAM DESIGNED TO SEE IF PEOPLE ARE ELGIBLE FOR PLATINUM CARD. USE FUNCTION Get_Credit_Limit() to prompt user for customer's present credit limit. function should return credit limit. Use Get_Acc_Bal() to prompt for customers account balance. function should return account balance. Use function Determine_Action(0 whose arguments are customers credit limit and account balance. Determine_Action() should return 0, 1, 2, according to following. If customer had credit limit of at least 2000 and account balance of 500 or less, bank will issue the customer a platinum card. in this case, function should return 2. If a customer has credit limit of at least 2000 and an account balance of more than 500, bank will send a letter stating that if customers balance falls below 500, he or she will receive platinum card. in this case, return 1. if customer does not fall into either category, bank will take no action. function should then return 0.
Use a function Display_Action() to display the action bank will take for customer. Pass value that Determine_Action() returned to Display_Action. Based on this value, Display_Action() should display message that shows what bank did: Issue Platinum card, send letter or take no action.


My question is how do I start off Main and how do I return the values 0, 1, and 2. I don't understand that part. I'm pretty terrible at this and this is what i have so far. any help would be greatly appreciated



#include <iostream.h>
#include <iomanip.h>



double Get_Credit_Limit(double);
double Get_Acc_bal(double);
int Determine_Action(int, double);
int Display_Action();



double Get_Credit_Limit(double credit_limit)
{
double credit_limit;

cout<<"\nEnter present credit limit: ";
cin>> credit_limit;

return credit_limit;

}

double Get_Acc_bal(double)
{
double account_balance;

cout<<"\nEnter account balance: ";
cin>> account_balance;

return account_balance;

}


int Determine_Action(int)
{

if ((credit_limit >= 2000) && (account_balance <= 500))
cout<<"\nIssue Platinum Credit Card";
return 2;

if ((credit_limit >= 2000) && (account_balance > 500))
cout<<"\nIf balance falls below $500, you will receive Platinum card.";
return 1;