This is my personal experience with the Arduino Uno R3.

My dad bought me an Elegoo UNO Project Super Starter Kit.

http://www.elegoo.com/product/elegoo-uno-project-super-starter-kit/

In the tutorial, it starts you off with the Blink program.  If you look at your Uno R3 you would see a blinking light. There is a program that lets you control the amount of time (in milliseconds) so the light will be on or off. I estimated the amount of milliseconds I wanted so I can do the rhythm of Beethoven’s fifth symphony, we replicated the existing code all the times necessary, then modified the number of milliseconds in each instruction to make it blink in the same rhythm as the classic dun-dun-dun-duuuuuuuun!