I wanted to know if there is anyway to include the vertical bar of binomial uncertainty itself in the plot in histogram.
For every bin of your histogram, you can calculate its “error” (using its “content”) and then use TH1::SetBinError
In principle, one can use TH1::SetBinErrorOption to specify statistics for histogram bin errors from Poisson interval at 68.3% (1 sigma) or 95% (~2 sigma), and histogram error bars drawing options will use this information.
If you want other “asymmetric errors”, then you need to switch to TGraphAsymmErrors
For computing and then displaying binomial uncertainties, you can also look at the