Lfit with error bars, HELP PLEASE!

I am very new to ROOT and just learning it and I am having a problem understanding some of the tutorials and how to adapt them for my use. I have a very simple linear fit code that I would like to add error bars to. I am having a hard time finding a tutorial for error bars that is not so complex that I can merge it with my simple program. Does anyone have any suggestions?? I’ve pasted a copy of my code below.

#include "TGraphErrors.h"
#include "TF1.h"
#include "TRandom.h"
#include "TCanvas.h"
#include "TLegend.h"
#include "TMath.h"

void linearfit()
	Int_t n=6;
	Double_t x[6] = {1,2,3,4,5,6};
	Double_t y[6] = {139,99.75,88.4,121.8,90.6,149};
	Double_t c[6] = {1e6,.5e6,.25e6,1e5,.5e5,.25e5};
	Double_t e[6];
	for (i=0; i<6; i++)
		e[i] = y[i]*1/sqrt(c[i]);
   TCanvas *myc = new TCanvas("myc", 
      "linear fits");

   //Generate points along a 1st degree polynomial:
   TGraphErrors *gre1 = new TGraphErrors(6, x, y, 0, e);
   //Fit the graph with the predefined "pol3" function


Your graph has error bars . They are very small.