There are two ways to do this, either with a background, as part of a scene, such as on a table, with other things around it or "without" a background. If you're going to use it as part of a scene, than plan your point of focus and DoF accordingly; you want the flowers to be clear and sharp, but perhaps only a soft suggestion of the candleabra behind it.
Generally, I find a vase or other container in a subtle, complimentary colour, and use a large piece of smooth, black, cotton fabric behind it. Set this up so that it is wider than your field of view, and starts well above the upper-most part of the flowers, and is curbed under the vase/container. Ideally it should be a foot or more behind the flowers as well. Experiment with diffuse lighting and reflectors for best results. You don't have to buy a lot of expensive stuff for this; bleach or similar clear, translucent plastic over a desk lamp make great diffusers, and bright white to warm yellow card-stock/paper will work as a reflector to eliminate shadows.