Hi Bala and welcome to the forum
First, there is a greenhouse forum where you will find a lot of threads about greenhouse heating and winter growing.
https://garden.org/forums/view...
Most, and by this I mean 99.5%, of greenhouse kits are not designed for over-wintering or growing of plants during the winter in areas that get cold. There is just no insulation. You could heat it, but the cost will be phenomenal. It is like trying to heat your front porch! Also, you would need an alternative light source since the sun is low in the sky and days are short.
Greenhouses designed for year round growing in colder climates tend to be very expensive with expensive insulation and heat gain systems, in addition to artificial light sources. You could build one yourself, but it would take special skills and knowledge and would be expensive to build.
If you want to learn more about winter greenhouse growing, check out this site:
https://ceresgs.com/ They are one of the leaders in year-round greenhouses. They also have a great book that will help you understand how to build/buy a greenhouse for year-round growing.
https://ceresgs.com/resources/...
With that said, you certainly can use your greenhouse as a season-extender in the Fall and to get a jump on Spring with seed starting, but you will need a heater for cooler nights.
Your greenhouse temperature at night will barely stay above the outdoor temperature without a heat source. Remember, most seeds need warm soil between 70-90 (depending on the seed) to germinate. Without the warm soil, they will take a long time to germinate and the germination rate will be much lower. Think of using a heater and seedling heat mats for seed starting.
I know this is not good news for you, but I hope some of it is helpful.
Jim
