Google is your friend! Seriously though, The most basic three elements your plant will need is the Big three: NPK
wikipedia.org/wiki/Labeling_of_fertilizer or wikipedia.org/wiki/Fertilizer
That will get you on track as far as giving your plant or plants what they need for a good start, application rates vary depending on what your growing ( Veggies, Fruits, Flowers, Trees, Cactus..etc )
You can get really technical and have your soil tested if your growing in your native area's Dirt! This will help you adjust for deficiencies in your soil so your Crop will be more productive. Things like PH ( potential of hydrogen) are also in question as this will hinder or help your plants uptake of nutrients depending on where your readings are.
Water quality is also of big importance since this is the plants drink of choice and can have alot of minerals and Micro nutrients depending on your local area water source. Keep in mind that Municipal provided water is treated in a way that strips these desirable traits away. I prefer ground water.
Not to cause you countless sleepless nights but like anything else in life if want great results you have to work at it.
These are just the tip of the iceberg, we still haven't covered Organic or Bio-Dynamic or all Natural fertilizer, we may need a few more hours!
If you plan on getting some decent results but don't wanna go all garden Nerd go buy some pre packaged soil like Miracle grow or Pro mix and water with some organic Fish Emulsion mixed in. Just my .02