Lighting, Light Fixtures, Ceiling and Exhaust Fans - hard wire to plug in - help

Bought a cute (decorative) little hanging light but it's hard wire...Home Depot guy told me to just buy an extension cord and some Butt Splices and make my own plug in type light. no problem, should be simple...BUT...since there's no color to coordinate on the extention cord (after I cut off the female part) to the hard wires....I'm lost... I read the "ribbed" part of the cord is neutral (white wire????)...is this true and does it go to the white wire? Thus, would the "smooth" part of extention cord go with the black wire?
As you can see, I don't do electrical, too scary, but thought no current running thru this, so should be a breeze....oh well! Thanks for your help.

Home depot guy is an idiot.
Find a plug lamp that doesn't need to be modified.

Thanks Joe. Guess I'll just use it for decoration and forget the light..(don't really need the light anyway)... It's not so cute I want the house to burn down! Thanks again

In general, it's a bad idea to hard-wire a fixture designed to be plugged in, or to plug in a fixture designed to be hard-wired.

But yes, the ribbed wire is the neutral and the smooth wire is the hot.

P.S. hummmm "Home Depot guy's an idiot"...makes me think maybe I should get a second opinion on what's been told to me by them about me re-roofing my house....LOL

Do not get electrical advice at the big box stores. It's like gambling. Most of the time you lose.