I've found a textbook online that teaches complete beginners how to program using Racket: do you think that seems like a good place to start?
Racket is a Scheme/Lisp-type functional language. Functional programming (Lisp, Scheme, Clojure, Haskell) is definitely worth knowing, but you should be aware that it is a lot less common than iterative programming (Python, Java, C++), so you may not find it as immediately and as widely applicable as you would if you chose a more popular language. What you'll probably find is that functional languages are a lot more theoretical and academic than iterative languages, so you might find it easier and faster to get up and running with actual, practical applications if you use an iterative language.
If you want to use Racket or any other Scheme, I would recommend two books. The first is The Little Schemer, an excellent and entertaining introduction to Scheme (Racket is a Scheme), which makes heavy use of the Socratic method. The second is SICP (
free online version here), which is widely considered an excellent and thorough textbook. That book is not easy material, however. I would recommend that you at least go through the The Little Schemer (just don't cheat), and consider SICP to be advanced material, which may or may not even be a good recommendation for you. But look at The Little Schemer for sure -- that book is fun.
Even if you go with Racket, I highly recommend choosing at least one iterative language to play with as well. If I had to do it all over again, I would want Python or Ruby to be my first language. If you're interested in front-end web technology, Javascript is a good choice. These are scripting languages, so they'll be a lot easier to pick up than, say, C++. You'll want to familiarize yourself with Object Oriented Programming (OOP), which is very widespread.
Anyway, feel free to ask me any questions you have.