How to access my histogram matrix to fill the histograms

ROOT
1

using namespace std;

//have 10 different flavors with leading and subleading options
enum flavors_t {GG= 0, GB, BG, BB, GQ, QG, QQ, G, B, Q};

//have 7 types of hidtograms pt, eta, phi, MET
enum histogramVariable_t {ptL =0, ptS, etaL, etaS, phiL, phiS, MET};

std::string flavorsName[10] = {“gluonGluon”, “glounb”, “bgluon”, “bb”, “gluonQuark”, “quarkGluon”, “quarkQuark”, “gluon”, “b”, “quark”};
std::string histogramVariableNames[7] = {“ptLeading”, “ptSubleading”, “etaLeading”, “etaSubleading”, “phiLeading”, “phiSubleading” ,“MET”};

//Need to specify the range of the bins
double lowBinRangeForVariables[] = {0, 0, -5, 500000};
double highBinRangeForVariables[] = {1000000, 5, 5, 500000};

//Matrix of histograms
vector<vector<TH1F*> > matrixOfHistograms;

for(UInt_t iflavor =0; iflavor<10; iflavor++){
vector <TH1F*> v_rowOfHistograms;
for (UInt_t iTypeOfHistogram = 0; iTypeOfHistogram <7; iTypeOfHistogram++) {
TH1F * myhisto = new TH1F((histogramVariableNames[iTypeOfHistogram]+flavorsName[iflavor]).c_str(),(histogramVariableNames[iTypeOfHistogram]+flavorsName[iflavor]).c_str(),100, lowBinRangeForVariables[iTypeOfHistogram],highBinRangeForVariables[iTypeOfHistogram]);
myhisto->Sumw2();
GetOutputList()->Add(myhisto);
}
matrixOfHistograms.push_back(v_rowOfHistograms);

}

now i want to fill each histogram

I am using matrixOfHistogram.at(0)[0].Fill();
I am not sure what should i use???

Thanks