Why does the gradient tool black out EVERYTHING instead of a gradient

[june_6376]

Well another pesky wall of inexplicable behaviour of Photoshop has just hit me smack in the face.
Learning via an online tutorial, I was introduced to the gradient tool.

Now, in the tutorial the mask was selected and then the gradient tool, and a perpendicular line was drawn across the photograph as you can see in the attached below.

Problem is, when I do the exact same maneouver, I get completely different and frankly inexplicable results.

The "gradient" tool, as the name implies, hopefully, has the sense to generate a gradient - which is the case in the tutorial. Seemed simple enough.

Funnily, when I do it Photoshop completely ignores whatever angle, length I draw the line and wants to black everything out. Covers the whole photograph with a black mask and if my eyes aren't deceiving me, I wouldn't call this a "gradient"

Left is the  photograph both the tutorial and I start with, and the result from the tutorial is above (gradient highlighted in red to transparent) and my results are below (completed ruins the photograph and blacks out)

And I frankly hope people would agree it's not a gradient.
Well I have zero idea what on Earth other toggles, cables, switches, conditions and buttons I need to press to make the gradient tool function, aside from well, selecting the tool and using it.

Does the gradient tool come with a default "no-gradient" option? Do I have to further tell how to gradient to the gradient tool? I am very much lost as always....if there's any information I can refer to, it would be tremendously helpful...

[Earth Oliver]

You haven't yet chosen the gradient preset or colors for your gradient. See that black color in your Options Bar up top? That's the current gradient. Change it.

So strange that people get angry when they don't know how to do something and will blame everyone but themselves.

[melissapiccone]

Choose your gradient from the dropdown in the options bar:

  

[Bojan Živković]

"Do I have to further tell how to gradient to the gradient tool?"

Yes, your current gradient isn't a gradient; it appears to be solid black, as mentioned in previous reply. I believe you're looking for a color-to-transparent gradient. You'll need to either select a preset for that type of gradient or create one on the fly before using the gradient tool.

Have you tried using a non-destructive option with the gradient on a separate layer? That might be a better way to learn how things work without affecting the original photo and without the risk of saving an undesired result over the original image.