I have one, a different brand. I cook on gas with it. Mine's fairly new.
Put it over medium to heat. Start mixing your batter. Flip the iron over to heat evenly. You want to get it fairly hot so don't be afraid of giving it more heat. I give it a shot of release spray (pam) before the first waffles are made. Lift the top plate and pour in a bit less than half a cup of batter. Experiment to find the amount that works with your size iron and batter choice as these are variables. Close the lid and flip the iron. I flip right at the start as I find the bottom plate hotter than the top plate at this point.
Watch the steam coming out of the sides of the oven. When it slows down, flip the iron again. You can give a light lifting pressure on the handles to check doneness. It should release with light pressure. If it resists much, the waffle isn't done enough and if you keep lifitng, you'll tear the waffle between the two plates. You'll have some trial and error the first time you use it to figure out timing.
I use a fork to help lift it out of the iron when cooked. Remove the waffle, close the iron so it doesn't tip over or fall. The bottom plate will be heating while you take the waffle to the table. Then lift the top plate, add more batter, close and flip.
If I were cooking on an electric coil, I would probably not use the outer ring as it wouldn't get hot enough. I'd want the iron in direct contact with the coil This will complicate the opening and closing of the iron. Same for an induction stove. I wouldn't use it at all on a glass top stove as you'll probably scratch the glass top.