Welcome to the boards! Let me start by saying you are already more mature than many your age because you did stop to ask questions before jumping in! No flames here!
On to your question. I don't think they are that hard to set up, but not cheap either. Already having most of the setup, you're ahead of the game. What you will need for CPs:
Light: I'm not sure of the light requirements of reptiles, but as far as that goes, for CPs a general setup would be taking off the lid, and try to get 4 bulbs over your tank, side by side. CPs need a lot of light. There are many threads here about the best type of bulbs, but generally as long as you are using fluorescents of some kind you will probably be ok. I use a mix of daylight and aquarium bulbs. Others use different bulbs. Putting them on a timer is a good thing as well, they should get 12-16 hours of light a day, depending on time of year and the plants grown.
Ventilation: Making sure you have air flow through the tank is important, perhaps with an old CPU fan. You need the ventilation to get rid of heat. Most CPs prefer temps ~70-80F during the day. A little temperature drop at night is a good thing. 4 bulbs will likely cook the plants unless you leave a lid off entirely. I can forgo the fan because my terrarium is lidless so there is plenty of airspace.
Humidity: Most plants are tougher than folks think. I give them plenty of humidity simply by leaving an inch or so of water (with an old aerator running in it) in the bottom of the terrarium. The plants sit in trays above this water. I use the 'cubes' they came in from the store as platforms and put the pots on them. This allows me to keep the tank cleaner and to separate out the plants that need winter dormancy easily. If you have reptiles you should have an RH meter in the tank already, if its above 50% you are probably ok.
Water: RO (reverse osmosis), distilled, or rainwater ONLY! Brita/bottled water is not good enough. CPs require extremely mineral-poor conditions to thrive. Tap water should be assumed to be too mineral-rich unless you can have it tested to determine otherwise. Most tap water and all bottled drinking water has minerals added to make it palatable to taste. If you use water *under* the water trays just for humidity, it can be regular water, but I use RO for everything just to avoid the mineral-ring buildup on the tank that I find unsightly, plus I don't need to worry about making a mistake that way.
Soil: Long-Fibered Sphagnum (LFS), Sphagnum Peat, clean silica sand are musts. Other things like vermiculite, perlite, are extras some people use as additives, but many of us find it isn't strictly necessary. Some of us use nothing but the LFS and do fine. If you really want to avoid algae (nigh-impossible) you can microwave or bake the soil before potting plants in it, this will kill any spores in the soil.
Other/Misc: NO FERTILIZERS!!!! I can't stress this enough. Avoid everything with the name Miracle-Gro, because they add fertilizers to everything. Remember CPs thrive in poor soil. Fertilizer will kill them. As for other additives, a fungicide of some type may or may not become necessary at some point. Wait and ask if it becomes an issue later. Accept the fact that despite all your efforts, algae will grow; mostly it is harmless, ignore it (a hard lesson for me). Pick up a copy of the book 'A Savage Garden' by D'Amato, it is practically the 'bible of CP growing'. Its an invaluable book.