method of heating

[paulkane1]

hello, i am a complete novice on all things gardening, but i have bought a 6x6 gardman greenhouse, i have just finished , a 18'' inch base with facing brick , the whole way around the base , first of all, before i put my greenhouse on top of the brick base. i am not to sure exactly, what area that gives me to heat,but i have been reading various articles on heating, and to be honest, i am none the wiser what form of heating to choose. the most obivous factor is cost to heat the greenhouse, I have outside electrical fittings , from a shed that i had previous, right next to the greenhouse, if i was to go for using an electrical heater, 1, What kilowatt heater would be suffice to heat this area, 2, As i am a novice, i will be starting of with not to hard of plants and veg to grow, but i intend to use heating cables for propagation of seeds etc.So would i only need heat to keep the frost at bay ? Can anyone recommend a good economical electrical heater,but more important , stays within the tempature required ? As i say, i am a complete novice, first venture into GREENHOUSING,i know i will make mistakes, but if anyone can guide me , i would be grateful. Yours Kindly paul