How much should you water and give light to dracaena marginata?

I recently bought a dracaena marginata plant for my room that's about 9 inches tall from soil surface to top about 4 days ago. The leaves on the sides and bottom are turning yellow and wilting, even though I watered it recently with about a quarter liter of water, and I put it near my window to get bright light, but not close enough to get direct sunlight. Am I doing something wrong? I want the leaves to stay nice and green like how professionals care for it.