Your light source needs to be really close during seedling phase. I use Marijuana for my Multiple Sclerosis neurological pain. I just started growing it but I grow alot of different plants.
You can actually grow a plant to harvest under one of these lights I posted a picture of. Cheap enough on Amazon. It's all my friends dad uses
Re-pot that leggy (stretchy) plant in a deeper pot almost up to your first set of leaves.
Get it back under the light with just a inch or two above. If your light source is hot, you will have to adjust it accordingly or it will burn your seedling.
Don't over water. It doesn't need a lot of water right now and it will not help.