A backyard garden starts with one thing first;
It cannot be in direct sunlight, though it will require plenty of sun. Plant your vegetables that need more sun in part of the garden that gets the most exposure. Tomatoes for example, love sunlight.
The soil where you plant your garden is the second most important element. Don’t reply on the soil your vegetables came in, as the roots will start to grow as the plant gets larger.
Too much will kill your plants, too little will kill your plants.