Do I need one like the manual says. It's a 2 gallon tank or so why do I need a float switch and how install put inside of a small tank?

How do you intend to turn the pump on and off? What do you mean by 2 gallon tank?

That's if you have a holding tank I believe.

You can run a pump without a float, but without a shut off other than you being there, you run the risk of burning the pump up, or overfill a two gallon tank. I cannot see where a two gallon tank is even practical in a water delivery system at all so PLEASE define the PURPOSE of your pump. Got a well or something? What's the little tank all about?

If you have an idea to straight pump water to your house forget it! What are you trying to accomplish?

What manual are you referring to?