Very basically, the nutrients plants need through fertilizer are nitrate, phosphate, potassium and traces (iron etc). To add these you will need the following:
KH2PO4 (phosphate and potassium)
KNO3 (nitrate and potassium)
If your tapwater is soft and low in calcium or magnesium etc you may also need CaCl (calcium, chloride, one example) and MgSO4 (magnesium, sulfate, epsom salts).
It is also advised to have some bicarbonate to assist in plant growth, particularly in low tech tanks. Also necessary to prevent wild pH swings when injecting CO2. A KH of 3-6 is generally recommended for this purpose. You can use bicarb soda or place crushed coral, shell-grit etc in your filter to increase KH.
Go to Aquarium Nutrient Calculator
for calculating dosages, solutions etc.
This tank won't need much fertilizer, only slow growing plants. Start conservatively with your dosing and increase slightly as needed.