Here are a few elements you may have. Fabric, lights, flowers, balloons, letters or numbers. I will get into details of how to incorporate them later.
Next lets think setup. There are two ways to set up a backdrop. Hanging or standing.
-Hanging. Take a look at the space you will be putting the backdrop. How high are the ceilings? Could you hang a pole? If you can hang a pole from the ceiling this is the easiest option. You can use a 1.5 inch pvc pipe or any other pole that will not bow under the weight of your backdrop.
-Standing. Creating a standing back drop is a little more labor and cost intensive. The easiest option is to rent backdrop pipes and bases. Many rental companies will rent you the pipes and bases at a low price if you pick them up. Or you can create one using pvc, wood or other building materials. The number one issue I see with homemade backdrops is problems with getting it to stand. My best advice is sandbags.