So I know little of the saltwater world so I can't draw a lot of comparisons between the two. I do know that plants are supposed to be more forgiving then say coral.
Basically when started off you need to have enough light for your plants, some kind of fertilization, and thats really it. Some plants work best planted into substrate, others can't be but that's specific to the plant. So we need to know so more information such as what light you have, and if you are running any fertilizers at all currently. Also what substrate you are using. Water parameters are helpful as well. Also assuming you are using a filter, what is it and what are you using for media in the filter?