Again, no code tags. And it looks like you are just taking stabs in the dark with no real understanding of basic C++ code structure. All you are doing now is declaring a global int variable called main, not a function. No opening braces at the end of the declaration either. Even if that was a valid way to declare main, you STILL have the print_even function definition INSIDE it.
// Header stuff
// Declare Global variables
// This is a function called print_even
void print_even(int firstNum, int lastNum)
// this is a local variables
int currentNum =0;
// put some code here
// your program starts here
// This is a call to print_even passing 2 values
I recommend doing the hello world tutorial. Google it.