QVariant MyModel::headerData(int section, Qt::Orientation orientation, int role) const

{

    if(role == Qt::DisplayRole) {

        if(orientation == Qt::Horizontal) {

            switch (section) {

            case :

                return QString("first");

                break;

            case :

                return QString("second");

                break;

            case :

                return QString("third");

                break;

            default:

                break;

            }

        }

    }

    return QVariant();

}