No one can tell you how much to open air intakes and damper setting since the chimney, elevation, atmospheric air pressure, outdoor temperature, and many other factors change the operation.
First, make sure the Insert is connected to a liner. You should be able to look up the outlet with a flashlight or mirror to see if there is a pipe connected to it, running up the chimney. If you can't see it, remove the upper faceplate cover to look at the top of insert. It should not have the open outlet in the fireplace letting the exhaust up the chimney without having a stainless steel liner connected to the Insert. If you're looking at a hole in the top of insert and damper, you need a liner connected to the Insert.
As a rule, open both intakes 2 or 3 turns. Open flue damper fully. The flue damper is a chimney control that slows the velocity of rising gasses. This in turn slows the incoming air. So a flue damper is a chimney control that affects the stove. Keep it open until fire is established. Open it every time before you open doors. Keep it wide open until you know how to control the fire with intake air dampers.
As it starts burning larger pieces, slowly close air dampers (intakes) to about 1 turn each. This should be about right to continue burning and bring it up to temperature. Depending on chimney flue (insulated, interior or exterior) you can then close flue damper partially. This will slow the fire even more. Too much damper will slow the draft resulting in increased creosote production. So you have to check it frequently until you know how much creosote you produce. The object is keeping flue temp above 250* to the top, so the better the insulated flue, the more you can close the dampers. Warmer weather may only require the air dampers open slightly to 1/2 turn. The more heat needed, the more open. Err on the side of opening the flue damper too much. Old installations where there was no insulated liner, and using the existing larger flue for the fireplace required tons of heat to be left up, using the flue damper little to none. The better the flue is insulated, the more you can use it, not needing as much heat to be left up. It has a flat side to prevent fully closing.
If you have a screen for fire viewing, the flue damper becomes your only fire control. With screen in place, established fire, slowly close flue damper until smoke rolls in at top. Open slightly to allow smoke to evacuate, preventing some of the heat from escaping. That is the setting for open door burning. It is not considered a radiant heater in Fireplace Mode.
