If you have a back yard, start growing anything at all. Get experience. Tomatoes and lettuce are trivially easy to produce. Herbs, peppers too. Potatoes might not be a bad experiment, in a barrel.

Best to lay away a good supply of white rice and beans, which will store. Together, rice and beans give correct amino acids. Also stock powdered milk. Powdered egg is usable for baking but lousy for omelettes and scrambled eggs - always gritty texture. Corn grits store well too. Tang and some Vit C. Hard red winter wheat and a grinder will get you bread, but you need yeast, or learn to make sourdough starter.

The big problem is you can't produce meat, in the city. You might do rabbits but not going to get away with chickens, goats, cattle.