Heating in my 89 Civic

The thermostat setting for heating is required to be put on high (3/4 of the knob turned clockwise) for me to start getting any heat, and hence I believe I may need to change the heater, or whatever that brings up heat. Please help me on what it is I need to change, and how. thanks.

That sounds about right. Those knobs get worn out after the years. Sometimes there will be play but you have to take it easy. I turn my knob all the way this time of year (in the mornings at least) and blast the heat until the car is warm and then use the recirculate button and adjusted the 1234 switch as necessary. Since our cars lack power, I usually cut off the heat when accelerating unless I'm freezing my ass off, then acceleration waits...