Boy do I need to educate myself about all this!

I don't know how to explain what tank I have except to say that from the top the tank is shaped like the superman symbol. This tank is small and only have this thing that blow bubbles(what is that called?).

I have one plant that have long leaves and I can't say what plant it is because when I bought it at Petco, this plant was with the other plants and it is not like it was all labled. The fishes I have in that tank is two guppies (male and female) and one fin-something tetra it's silver with black.
I plan on getting a bigger tank but right now I'm broke so it will have to wait a bit longer. Right now they are all happy(it's just too cute to see them play). I just wanted information about plants like what are the rules for live plants and are they better than fake ones. They were not eating the plants, it was just the leaves were falling off and dying so I would fish it out and throw the leaves away. They like to hide when they want to sleep or be left alone. I don't like asking the people in petstores because they are not educated enough to answer complicated questions.

Besides, isn't this why this forum exist? What would I do without you guys?!
This is my goal: educate myself with enough information about fishes, tanks, testing, and plants before I go out and buy a new tank and more fishes.
Today I had to do something for my husband and I had time to kill. I spotted Petco and you bet I drove up and park my car and ran in!

First thing I did was go to look at all the fishes and they looked so beautiful and healthy! If only I wasn't broke!

I saw some beautiful happy fishes of all kinds and colors. Then I saw some betta fishes and most of them looks so depressed it broke my heart!

How cruel!

It was SO HARD to walk out of that store empty handed.
So any information you can give me about live plants and differences between live plants and fake plants, etc. would be great.
Thank you in advance
