Editbox() is declared as a member of class Find. Your implementation of editbox() doesn't show that it is part of the Find class. Add this (in red):

Code:
#include <iostream>

using namespace std;
#include "Find1.h"
#include "Unit1.h"

void Find::editbox(AnsiString edit)
{
 edit = Form1->Edit1->Text;
 Form1->Label1->Caption = edit;
}