Don't know have a clue what you bought and I hope it works for you.
This is what I'm doing. I bought a flame weeder for about $80. I hook it up to a propane tank. I get it started and take it down as low as it can go, but still hear it.
Then I just wave it on top of the weeds long enough to see wilt. You don't want burn because it reactivates them and it will be 100 times worse than before you started. Heat reactivates the suckers.
You just want the heat to destroy the cells. It works best when the weeds are already cut or on brand new weeds.
You just wave it across the weeds once or twice. If you see burning while you're using it, you did it too long.
Mine is from Red Dragon. I spent big bucks to get a little handtruck for it. The handtruck is great in itself, holds a 20lb propane tank properly. The tie down situation, it comes with, sucks. It also cost twice as much as the flamer. My other beef is it's a pita to hook it up to the tank, so I'm going to spend some bucks getting the connection redone by a local propane company.
I only use it on days that have heavy dew or raining. It's come in handy during the few ice storms I get in my area.
I mean what I say about waving it across the tops of weeds. My brother, Dad and a neighbor didn't listen to me. My gravel driveway became nothing but weeds, after their 'help'.
A heat gun would give you the same effect, if you have the extension cords.