To create histograms:

   TH1F *h1 = new TH1F("h1","h1 title",100,0,4.4);
   TH2F *h2 = new TH2F("h2","h2 title",40,0,4,30,-3,3);


To fill histograms:
   
   h1->Fill(x);
   h1->Fill(x,w);
   h2->Fill(x,y);
   h2->Fill(x,y,w);

To set histogram style:

   void SetHistLineColor(Color_t color = 1)
   void SetHistLineStyle(Style_t styl = 0)
   void SetHistLineWidth(Width_t width = 1)

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