如何win32制作一个登录界面，我卡住了，不知道接下来代码该怎么写

case WM_COMMAND:
    switch (LOWORD(wParam))
    {
    case IDC_BUTTON_LOGIN:
        {
            // 获取编辑框中的文本
            HWND hUsername = GetDlgItem(hWnd, IDC_EDIT_USERNAME);
            int len = GetWindowTextLength(hUsername);
            char* username = (char*)malloc(len + 1);
            GetWindowText(hUsername, username, len + 1);
            
            HWND hPassword = GetDlgItem(hWnd, IDC_EDIT_PASSWORD);
            len = GetWindowTextLength(hPassword);
            char* password = (char*)malloc(len + 1);
            GetWindowText(hPassword, password, len + 1);

            // 如果用户名和密码匹配成功，弹出消息框并退出对话框
            if (is_valid_user(username, password))
            {
                MessageBox(hWnd, "登录成功！", "提示", MB_OK);
                EndDialog(hWnd, 0);
            }
            else
            {
                MessageBox(hWnd, "用户名或密码错误！", "提示", MB_OK);
               
                // 清空编辑框
                SetWindowText(hUsername, "");
                SetWindowText(hPassword, "");
            }

            free(username);
            free(password);
        }
        break;

    case IDC_BUTTON_RESET:
        // 清空编辑框
        SetWindowText(GetDlgItem(hWnd, IDC_EDIT_USERNAME), "");
        SetWindowText(GetDlgItem(hWnd, IDC_EDIT_PASSWORD), "");
        break;
    }
    break;