Unless cost is a factor, I would suggest being kind to yourself and find a backing that was printed and similar in color to the top quilt. Since this is your first time quilting, you want to have as many advantages as possible.
If the top is similar in color to the background, you won't have to worry if the bobbin thread shows through every once in a while and you won't have to worry about the high contrast of the backing showing through to the front of the quilt.
A printed background will not show your stitches as much as a tone on tone fabric or a solid fabric. If you are doing free motion quilting for the first time, you will want your stiches to not to show, because until you have some experience under your belt, you may have a few stitches you'll wish people couldn't see. Of course, once you wash the quilt a lot of the 'oops's' will melt away into the quilt.
Doing practice on some pot holders will help give more experience and control to your free motion quilting. The name of one the 'queen's' of free motion quilting (her name escapes me) says that before she starts quilting anything she practices for 15 minutes on something WITHOUT any thread in her machine. She says it gives her the rhythm she needs to start quilting.
I am certainly not trying to discourage you in any way, but just offering some 'seeds of thought' for starting out.