Let me be the first of us to welcome you here SophieFoster. Without some help, we cannot easily determine what your problem might be. The questions about lighting intensity and type need to be compared to tank dimensions so we will also need to know what size tank you have. The folks in most plant situations talk in terms of watts per gallon of light. Another factor that sometimes impacts plant keeping is the spectrum of the light bulb. You will find ratings of fluorescent bulbs in terms of so many thousand K. A daylight spectrum is about a 5500K bulb but planted tank people often use bulbs anywhere from about 5000K to 10000K. The 10000K is a very bluish looking light while a 5500K is slightly yellow, just like sunlight. Plant types and light levels will affect your success, so knowing what levels you have will let people help choose appropriate plants for your situation. There are appropriate plants for almost any lighting situation.