I have a Janitrol Thermostat with a Heat pump air/heat unit. There is a switch that goes from "Normal" to "EM. HT." with a red light under it. Can you tell me what this represents and what do I need to have it set on? I bought this house with the unit already installed. I do not have a manual. Also, do you know where I can get a manual? I looked online but I couldn't locate one. Thank you so much.

Emergeny ht means that it will turn on the electric heat strips in the airhandler to provide heat when the outdoor condenser/heatpump is not working or heating the house properly.
You do not want to run unless emergency due to high electric use

By having a heat pump you actually have two forms of heat. Your primary stage heat is your heat pump. Your secondary stage heat (aka them heat, aka auxiliary heat) is either heat strips inside your air handler, or a furnace (natural gas, propane, oil).

When the thermostat is on Normal the heat pump runs first and then your them heat if needed. This typically give you the cheapest operating heat. When the thermostat is set to EM HT, the heat pump is prevented from running and only your secondary heat runs.