Plant food? You don't mean like pellets for plants right? xD
Well when you say plant food it usually means things like root tabs, fertilizers, light, and CO2.
Anubias and floating plants would most benefit from a liquid fertilizer like flourish
Two most common roots tabs are seachem and api tabs which are best for root feeders. Liquid fertilizers many people suggest seachem flourish which is a liquid fertilizer like DanielaMarie stated and mostly used for water column plant feeders. Fish will naturally give off the CO2 but if you desire plants to grow faster, people will setup CO2 systems or use CO2 in a liquid form such as seachem excel. If you're doing low light plants than liquid fertilizers and CO2 are not really needed unless again, you want to see fast plant growth.
Seachem makes a number of different "plant foods" ranging from the "flourish" which contains a bit of all the nutrients to "iron", "potassium" which are specifically for that type of nutrient.
There is the dirt tank method which in very simple terms is having a layer of "dirt" covered with a cap, usually sand or fine gravel. Using this method plants absorb thier nutrients from the "dirt".
The type of lights depend on the plants being grown but generally you want a light that has a spectrum of 5,000-8000? I'm not exactly 100% on the lights.