I don't know what I'm doing wrong?

iim growing a few plants in my room and it seems like the plants are dying. my morning glory is wilted and leaves are turning yellow and some are very weak. its about 2 months old and about 30 inches. i have cayenne and bell pepper plants and they are doing something similar. my cayenne is doing fine now but the bell pepper leaves are falling off but they don't have any discoloration to them.On one of the bell pepper it looks like it has a little spider webbing around it. they are in a little green house. my maple tree which is little (not sure how old) but it was doing fine outside til i brought it inside. now the leaves are starting to turn all hard and crunchy but the color is still the same. I water these plants as needed and use a 23w 6500k cfl for lighting. i did have a gnat problem a couple days ago and tried to kill them when seen. could that have anything to do with my problem?