Ok, you've got 243L/64USG tank and 80 watts of T8 light which puts you at 1.25 watts per US gallon which is an excellent lighting level for what we call "low-light" approach to growing plants. The 15,000K may have been a marine type of light and I'd recommend 6700K as a better color for freshwater but that's not terribly important. The 17" is not too high I don't think, meaning no special worries about the light fanning out too much from being too high above the substrate. So one of your basic worries is out of the way.
Since you've got good light for low-light technique you will not want to use CO2 (kind of advanced anyway for now) and you will want only minimal "nutrient dosing" (which is our fancy term for giving the plants some fertilizer.) The next important think will be sort of the dual thing of figuring out your plant species and/or learning about species that are good for low-light technique (java ferns, java moss, anubias, crypt.wendtii, swords, many more.) Once you get the pic thing figured out you may need a post in the planted section to get the species figured out.
~~waterdrop~~