Phew, that title’s a bit of a read. In the future it might be best to shorten it, and place details in the post. 
Easier to read, and it’s easier to search.
So what seems to be the issue? Something you don’t understand? An error message? The more info you give us the better we can help.
I see two things that are off, and a couple that could be improved.
First, your selector. The step seems to indicate they want you to style fieldset elements rather than fieldset classes. Using a period in a CSS selector indicates it’s a class.
Second, I don’t believe none is a valid value for padding/padding-left/padding-right. If you want to remove padding set it to 0.
On to improvements.
If you set padding to 0, what’s the use in setting padding-left and padding-right to the same? Seems a little redundant.
Lastly, I don’t know if they’ve taught it yet, but you could use the padding shorthand when you need to set all 4 sides at once: