first time grow

Well they are finally growing! Don’t know if they are the right size but they seem so small and delicate, almost like a piece of cress, they aren’t very sturdy, not sure if I should be feeding them something? Have no idea as everyone using so many different things to feed so less is best until I know. Gave them half litre between them of plain bottle water and around a 300 ml of diluted feed (Root It 4 ml in 300 ml bottled water) between them? Don’t want to over feed or over water, also don’t understand the growing techniques? Sure that comes later! I think I’m over thinking it all but I’ve spent a fair bit setting everything up and don’t want to ruin it! 🙏🙏🙏