In[2]:= CreateDocument[{
  SetDirectory[NotebookDirectory[]];
  WindowSize -> Medium,
  DynamicModule[
   {x = 100, dist = 1, path, data, fitdist},
   Column@{
     Grid[
      {{TextCell@"Choose Distribution:",
        PopupMenu[
         Dynamic@dist, {1 -> "Normal", 2 -> "Poission",
          3 -> "Binomial", 4 -> "Maxwell", 5 -> "Uniform"}]
        },
       {TextCell@"Number of samples:",
        InputField[Dynamic[x], Number, ImageSize -> 100]}
       }
      ],
     Button["Generate & Plot",
      Which[
       dist == 1,
       CreatePalette@Histogram[RandomVariate[NormalDistribution[], x]],
       dist == 2,
       CreatePalette@
        Histogram[RandomVariate[PoissonDistribution[1], x]],
       dist == 3,
       CreatePalette@
        Histogram[RandomVariate[BinomialDistribution[40, 0.5], x]],
       dist == 4,
       CreatePalette@
        Histogram[RandomVariate[MaxwellDistribution[0.5], x]],
       dist == 5,
       CreatePalette@
        Histogram[RandomVariate[UniformDistribution[], x]],
       True,
       CreatePalette@
        Histogram[RandomVariate[NormalDistribution[1, 3], x]]]
      ],
     Row@{
       FileNameSetter[Dynamic@path],
       Button["Plot", {
         data = Import[path],
          CreatePalette@Histogram[{data}]
         }
        ]
       }
     }
   ]
  }
 ]