This is not complicated, simply put, bleeds are the areas of print at the edges of the printed piece that will be cut off in the bindery. See these two pictures before and after triming down the job. So if you want bleeds just extend your art off the edge of the page about an eighth of an inch in your electronic file. Make your document the actual size it will be after trimming. For example, a business card document is 3.5 by 2 inches, bleeds or not.