Planting a Garden

So....I want to plant a garden in my side yard. The spot gets plenty of sunshine and will be watered by the sprinkler (so that shouldn't be an issue). Does anyone know where I should start?

Is it too late to plant carrots, tomatoes, beans, peppers and squash? Do I have to buy fertilizer/top soil before I plant them or can I just plant away? Please share any knowledge...