I have anubias in the gravel at about 2-3" deep. Lower the water level a few inches, it will make it easier to plant. Use one hand, with the plant roots completely out of any basket/fiber it may have come in (if the roots are out freely, just be sure to free up the roots, open up a gap in the gravel (gravel should be at least 3-4" deep)...in time the roots will find their way throughout the gravel, the gravel should not be too large, should be about .03mm, very small or else the roots will not be able to spread out due to the weight of the pebbles...as your fingers "dig" down into the gravel, the roots will go with it, make sure the roots are (again) 2-3" deep OR that the gravel is not above where the base of the plant is, then cover the roots with the gravel.
Usually a plant can be buried in gravel with one hand, but if you feel better with a two hand process, this is fine.
Flourish tablets provide all the necessary nutrients.
you will find some plants work better than others. for instance, at first, I had anubias and wisteria. the wisteria did not take too well in the newly cycled tank whereas the anuibas thrived (I still have the first anubias plant, and it is still flourishing and plenty green, all without co2), whereas the wisteria began to decay, and in time, I was forced to throw it out...if any plants die or begin to wither, it is best to rid the tank of these leaves or else it wil cause pollution in the tank, and believe it or not, will force the other plants to suffer
anubias, of any type, is the best way to go. anubias can be grown in low light, under still or moving waters, need very little pruning (it is a slow grower), is not picky in terms of temperature or hardness, can maintain itself well if the nitrate levels rise a bit, and has no need for co2
so if your plants wither at first on you - I am unaware of the plants you have; if you could provide what types of plant, this would help me much - your best bet is to buy anubias (just a suggestion)
if you need further explanation as to how to plant, let me know