I'm new to gardening but would like to get a raised bed started in my NYC backyard. My plans are to build a 2x8 raised bed. I have a spot picked out but I am worried about drainage problems as the concrete is somewhat lopsided and uneven. I have attached pictures to show where I intend to place the bed (green and red concrete). I have also attached photos of a second location of where the bed could go but I would rather it be in the first location (regular concrete). The first location gets more sun. Would it be possible to level bed using wood chocks as needed once I set it up? Also, is 2 feet wide suitable for a raised bed? I see most people go 3-4 ft but 2 ft would suit my location better. I appreciate any help in advance thank you all so much.