In general, there are two main methods to growing aquarium plants. With, and without CO2.
With CO2 you will need to dose a lot of fertilizers at least once a week, and you may need to do a large 50% removal of old tank water and replace it with new water once a week, and you will need to ensure that CO2 levels in the tank water don't go too high. You will also make much more use of such an aquarium if you have a good quality light too.
Without CO2 you will dose less fertilizer, you will need to be careful with how much light you provide, and you won't do so many larger water changes. Using the typical "non-co2" method you won't have to worry about over-dosing fertilizer either.
The difference is a lot of money, a lot of time, a lot of growth speed and some specific species of plants which just won't grow without CO2.
I highly recommend reading this simple summary of the method without CO2 by Sudeep Mandal here:
How to Setup a Low-tech Planted Tank: Planted Aquarium Guide ? Welcome to Sudeep Mandal's spot on the net
It truly covers all the basics. It's the method I use, and many others on this forum do too, it's generally easier, and it's a much better spot for someone brand new to the hobby to get started. There is a lot more room for error, fewer things to keep track of, and you'll get a good grasp of the basics.
CO2 is great. If I had the equipment I'd use it. But if you aren't planning on putting a ton of plants into a tank, your really wasting your money. It's kind of like buying a really nice car to drive to work, when you live across the street from your job.