Well you should have germinated it before planting it, but its ok. Just keep the soil moist, but not soaked.
The more direct sunlight the better. If you can get it in a spot where it gets direct sunlight all day, then you will have a pretty solid grow.
As for can you grow in a 16oz cup... umm does this answer your question
By the way those arent my plants. They were taken from a contest held at another website to see who could grow the best plants from start to finish in only 16oz cups.
I wouldnt do it though if I were you lol, just transplant it into a 5 gallon bucket after a 3-4 weeks.
Goodluck