How does one use the information from a ticker tape?

You put the tape in a machine the reads the tape uses a teletype machine.

https://www.google.com/search?client=firefox-b-1-e&q=machine+the+reads+the+tape+uses+a+teletype+machine#fpstate=ive&vld=cid:9104e3bf,vid:beQlLqa9kzQ

I used to go in with my dad on some Saturdays, when I was 10 or 11, I’d get the tapes and run them through the teletype machine, got real good at replacing the ribbon too !

You decide whether you should but or sell stock. It was the late 19th century equivalent of the interent.

The ticker is a record of each of the sales on an exchange. People watch the ticker to follow the movement of the price of a security. One can then see if the price is moving up, down or staying flat.

The Dow Jones Industrial Average is not published directly on to a ticker, one must calculate it by using the last sale of the thirty component stocks. Financial information companies (such as Bloomberg) will do the calculation and then disseminate it to news services such as CNBC.