How to prompt user to upload image and display that image using shiny?

hello,

I am a beginner to R studio. I'm trying to prompt a user to upload an image and display it. here is what I have so far:

for ui.R

require(imager)
require(shiny)
require(jpeg)
require(png)
library(shiny)

shinyUI(fluidPage(
  titlePanel(title = " Skin leison Image Classifier"),
  sidebarLayout(
    sidebarPanel(tabsetPanel(id = "tabs", 
                  tabPanel("Choose Image", fileInput('file1', 'Upload a PNG / JPEG File:')),
                  #tabPanel("Use URL", textInput("url", "Image URL:", "http://"),
                  actionButton("goButton","Execute")
                              )
                ),
    mainPanel("Image")
     #         imageOutput("Cat")
    )
  )
)

and for server.R:

library(shiny)

shinyServer(function(input, output){
  output$Cat <- renderImage()
  
})