Ditto to core strength. Weak abs, bad posture and tight hip flexors are all common contributers to typical back pain.
In your case it sounds like you were doing some lifting; we've all heard the old advice of lift with your legs not your back. But it really is difficult to do, especially when dealing with awkwardly sized stuff. Even the best of us get a little sore after doing more work or lifting more than we usually do.
Get it some rest, otc drugs if that's your thing, and/ or a massage.
To prevent it in the future, when someone asks you to help move, just say "no." :laughing: Or seek out some additional core strength and get your body used to using those muscles more. We carry things in the front usually so the back is under extra strain to keep us upright and balanced, even if we did lift with our legs. Build up the body's ability to take more punishment, practice the best way to use the body efficiently and with least impact. There are loads of great ways to do this, group exercise, personal attention form professionals, even some decent books out there as was just suggested above.