Hey! In this tutorial, I'm going to tell you how to make a scoreboard that shows your kills!

First, you need to enter this command:
/scoreboard objectives add Kills totalKillCount

Then, enter in this command:
/scoreboard objectives setdisplay sideBar Kills

And there you have it! Now, you can see how many kills you have gotten.

Note: At first, the sidebar will not appear. It will appear once you have one kill.