doesnt really have to be very exact, something like
5parts peat moss
3parts perlite
1part black kow/mushroom compost/organic compost
maybe a little vermiculite is you like
dolemite lime at about 1tbs per gallon
once you make some you will start to realize what you like. I just use coco and perlite now. You can find coco coir a pet stores if your interested in mixing some of that in. They sell brick, ground fine, chunks, and they also have clay pebbles called hydro balls too. They all make great amendments to your soil.