...most of the examples don't work for me (because they assign the data to a variable "data", which is apparently illegal because the name "data" is more than one letter)...:

What are you talking about?

data is a perfectly valid symbol name.

Well, if you want help, then provide more info about why you think you can't use data as a symbol name. Did you get an error message? Can you provide a sample notebook that demonstrates that it doesn't work? Are you sure you're using Mathematica, and not Wolfram|Alpha?

Maybe it has something to do with a trial version, but that seems like a stretch to me.

But whatever, I'm telling you, as someone who has used Mathematica for over 25 years, that you are absolutely not restricted to single character symbol names. Why would they put such examples in the documentation if you can't use them?

No, those are different products. If you're trying to use CandlestickChart then you should be using Mathematica. The product naming can be very confusing, and I think they are trying to finally unify products, so you might find it called Wolfram One, or some other variation. But if what you're using has "Alpha" attached to it at all, then that's a different product.

I'd suggest you contact Wolfram's customer support and make sure you're evaluating the product you really want to evaluate. Maybe you do want Alpha, but it sounds like you want Mathematica.

Yay! Now it all makes sense. I'm not very familiar with Wolfram|Alpha or Alpha Notebooks, so that's why I couldn't understand the problem before.