Hi Aaron and Welcome to the beginners section!
Yes, you'll probably look back on it someday as not a set of choices you wanted to make but no worries, you've now stumbled upon one of the best possible things that could have happened to you in the tropical fish hobby. This is a great forum with fun members and lots of great help usually.
I would divide your problems into two sets: the fluval edge has its own set of issues to work around and you'll want to be patient and try to get up with some of the other members who have them and know the issues and workarounds (if indeed they agree there are any issues!) The other set of problems are just the standard beginner ones we deal with dozens of times per month!
When fish move water through their gills to obtain oxygen, they also give off carbon dioxide and (!) ammonia, as waste. Fish waste, excess fishfood and live plant debris also are broken down in the tank to produce still more ammonia. Ammonia, even in tiny amounts causes permanent gill damage, leading to shortened lives or death. In nature, ammonia is immediately diluted by thousands of gallons of fresh water. In our tanks, even very big ones, it quickly reaches a concentration that can cause these problems.
The hobby has a very curious tool, called the "biofilter" to combat this problem. This is going to sound weird but we actually -grow- two specific species of bacteria to help clean our water. The first species "eats" ammonia (we'll call them A-Bacs, for Ammonia Oxidizing Bacteria.) They process ammonia(NH3) into nitrite(NO2), carrying along the Nitrogen atoms to a new stage in a thing we call the "Nitrogen Cycle" of environmental science.
Unfortunately, Nitrite(NO2) is -also- a deadly poison to fish! Nitrite, even in tiny amounts, causes nerve and brain damage, leading to shortened lives or death. But our second specific species of bacteria (we'll call it the N-Bac species, for Nitrite Oxidizing Bacteria) "eats" (since its single-celled, it doesn't really "eat" but "processes") the Nitrite(NO2) and produces a product called Nitrate(NO3.) Nitrate(NO3) is also somewhat bad in our tanks but not nearly so much and the first two substances and so nitrate(NO3) can be removed via our weekly water changes.
The process of growing the correct two species of bacteria to create a working biofilter is called Fishless Cycling and is done prior to letting any fish be exposed to the poisons. When beginners don't yet have this information and accidently get led into having fish but no working biofilter, we call this a "Fish-In Cycling Situation" and the members know how to help you deal with it. Large daily water changes, with good technique, are often required for a while in an attempt to keep the fish alive. Often not all of the fish make it, but if the hobbyist is diligent, it can be done.
The goal in Fish-In Cycling is to use a good liquid-reagent based test kit (most of us like and use the API Freshwater Master Test Kit) to measure the concentration of ammonia and nitrite(NO2) and to judge how much and how often to change water. The numerical goal is to try to keep both ammnonia and nitrite(NO2) just below 0.25ppm at a maximum until you can be home again (from work or school or whatever) to change water again. So you change most of the water in the tank and then the poisons slowly rise and you test and change most of it again as it reaches 0.25ppm. Depending on the fish load compared to the tank size, this can be either easy or quite a challange.
A fluval edge is not such a huge tank, so your water changes are not going to be too difficult compared to bigger tanks but because its small, the poisons can creep up on you very quickly. OK, now what do I mean by "good technique" during a "water change"? Well, you always need to use a "gravel-cleaning siphon" to stir up the bottom when you are removing water (this is because the nitrite and nitrate like to "hang out" down close to the gravel to some extent!) Then, since you have an almost non-existant bacterial colony in your filter at first, you need to "condition" your water (use a chemical that removes chlorine and chloramine) at 1.5x to 2x (but not more than 2x) what the instructions on the conditioner bottle say. You also need to roughly match the return water temperature (your hand is good enough for this) using just some hot water from the tap (unless you think you have too much copper from an old water system.) Whew! A lot of stuff, right?
But don't worry, the members love helping out and different ones will pop in and help you with your questons! Another thing (which I can't remember much about) will be to analyze the Fluval Edge filter and its "media" to be sure its got good types of media and not things that are unneeded (as many manufacturers like to sell you stuff you don't necessarily need, such as carbon!)
~~waterdrop~~
I asked the fella at the pet store and he's saying i could put a couple more small fish in but I'd prefer to get advise from some people who have the experience and know a tad more.
i read through it and you've explained it perfectly so i feel i know more about the cycling and how to avoid loss of my fish and keeping them healthy 
