HWND hEdit1 = GetDlgItem(g_hWnd, IDC_MAIN_EDIT);

// get string lengths
int selStart = GetWindowTextLength(hEdit1);
int selEnd = selStart + strlen(buffer) + 8;

// this calls the function to insert data before formating
insertMessage((HWND) hWnd, buffer);

CHARRANGE cr;
cr.cpMin = selStart;
cr.cpMax = selEnd;
SendMessage(hEdit1, EM_EXSETSEL, 0, (LPARAM)&cr);

CHARFORMAT2 cf;
memset( &cf, 0, sizeof cf );
cf.cbSize = sizeof(cf);
cf.dwMask = CFM_COLOR;
cf.crTextColor = RGB(255,0,0);

SendMessage(hEdit1, EM_SETCHARFORMAT, SCF_SELECTION, (LPARAM)&cf);