Be sure you know the requirements for the type of plant you are purchasing. Some of the  plants sold  aren't aquatic plants.  Other plants require  a lot of  light and  CO2  and some are low light and low CO2 plants.  I recommend purchasing the  low light and low CO2 plant if you don not  have a specific plant set up. There are a few stem plants that will work for you.

Go to a small local Pet Store around where you live instead of  a big chain like Petco or Petsmart and ask them what type of plants you can use.

what kind of plant do you have brigy?

I highly doubt that injecting carbon dioxide would be beneficial to the fish. I would just say get a fake plant. they're easy , and thhey dont need any sort of care. But if you want a real plant, well.... Id suggest going to your pet store and get them to reccomend a hardy plant that'll survive in all sorts of conditions... like someone else said earlier....

cambomba can be a good one..

Injecting cO2 into the aquarium water is completely reasonable, and does help the plants grow. But to me that feels like it's more complicated than it has to be.
Just make sure to have a good light, enough light for the kinds of plants that need much of it, and less for the ones who prefer shade. Even better, try out more different plants to see which ones will fit your aquarium, read about them in books... or simply ask in the pet shop for some good, hardy kind (:

Goldfish love plants!  It is part of their natural diet and there is no way you can stop them trying to make a meal of those beautiful plants you have just added.  Having said that, there are some plants that do better with Goldfish than others.  These include Vallisneria, red and green ivy, Blue Stricta, Bella Palm, Purple Waffle and PurpleTemple.  Elodea is an excellent plant, although it will be eaten quite quickly – it is cheap to buy, looks attractive until the fish demolish it, oxygenates the water, and is doing the fish good by providing some natural food.   Avoid the fine-leafed, more delicate looking plants, such as Foxtail or Ambulia, as your fish will dispose of these very quickly.

Also those plants will not live forever, they need to be replaced from time to time, as our fish love to nibble on them.
I do not advise to have fake plants, as they do nothing for our fish... and to be honest, for myself I do not like artificial things anyway, but this is up to everybodys preferences

Are you talking about the Topfin plants in the individual containers?
I bought some and mine have lasted and grew roots just fine.
What kind of lighting do you have on your tank?
If you have incadescent the plants won't grow as well.

I would reccomend live plants if you can. But I am so busy that I barely enough time to get ready for school! The good thing is I can get in my animal care everyday.