Your anemone is going to die. Period.
It is extremely difficult to keep small tanks stable. The smaller the worse it is. And this is for people who are experienced.
Here is the blunt part. You are new, you are not ready for an anemone. They are or can be extremely difficult to keep.
A 10 or 15 gallon, SOMEDAY, MAYBE would be able to keep an anemone. You will have alot of work to do to keep it stable.
This is as blunt as I can be while still being nice. I'm trying to be nicer in my responses while telling you straight so I don't waste my time typing.
Here is my tank so you know I at least know a little about what I'm talking about.