HDITEM hdi;
TCHAR  lpBuffer[256];
bool   fFound = false;

hdi.mask = HDI_TEXT;
hdi.pszText = lpBuffer;
hdi.cchTextMax = 256;

for (i=0;!fFound && (i < nCount);i++)
{
   pmyHeaderCtrl->GetItem(i, &hdi);
   
   if (strcmp(hdi.pszText, lpszmyString) == 0)
   {
      strcpy(hdi.pszText, lpszmyString2);
      pmyHeaderCtrl->SetItem(i, &hdi);
      fFound = false;
   }
}