do some research..I read for months and months before my 1st grow and im still always reading...
your going to get 100000 different answers to your question on what to feed them. You also didnt say what phase of growth your in(seedling,veg or flowering) the plants need different nutrient levels during different phases. I dont give any nutes until about 2.5 weeks into veg and start out LIGHTLY. Its better to start real slow then to ruin your plants with too much nutes.
Personally I recommend the fox farms line, but if your on a budget get some bat guano(high n for veg, high p for flowering), blackstrap molasses, and earthworm castings and you should be ok..
DONT FORGET TO DO YOUR OWN RESEARCH! Read read read.. every time I had a question about my plants I just searched rollitup. I guarentee all of your questions have been answered before.
GOOD LUCK!