OPENFILENAME ofn;
char* sFilename = new char[MAX_PATH];
sFilename[0] = '\0';

// Configurate the save dialog box
ZeroMemory(&ofn, sizeof(ofn));
ofn.lStructSize = sizeof(ofn);
ofn.hwndOwner = hWnd;
ofn.lpstrFilter = "Text Files (*.txt)\0*.txt\0All Files (*.*)\0*.*\0";
ofn.lpstrFile = sFilename;
ofn.nMaxFile = MAX_PATH;
ofn.Flags = OFN_EXPLORER | OFN_PATHMUSTEXIST | OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT;
ofn.lpstrDefExt = "txt";

if(GetSaveFileName(&ofn))	// Open save dialog
{

}