i need to make compost

I use sterilized dirt with my plants so i am going to either make my own compost or buy some in order to get the proper micro biotic life in the soil my plants need. Does anyone know what to look for in a store-bought compost, or am i just better off making my own? Do i need something with a high bacteria count or a high fungal count? And lastly any tips for making a simple compost tea so i can flush the soil with water high in biotic life?