Place the broken concrete pieces into a wheelbarrow and move them to the area where you want to make the flowerbed.
Remove the sod from your yard in the location you want the flowerbed. Press the shovel into the ground about 4 inches, then pry up the grass. Repeat along the edge of the area until you have the flowerbed's shape, then remove the sod from within the area.
Arrange the broken concrete pieces around the flowerbed's edge. You can place the concrete pieces randomly so that there is no obvious pattern, or you can select similarly shaped pieces and arrange them like a puzzle so that they fit closely together.
Fill the flowerbed with garden soil so that it is even with the top of the concrete pieces. Smooth it out using your hands or the shovel.
Dig holes in the soil and insert potted flower plants. Remove the plants from the pots first if they aren't biodegradable, such as peat moss or paper pots. Fill in the hole around the plants with soil.