I have a Nikon D3100 but I'm having problems printing my pictures

I'm not able to post them on Facebook or print them at Walmart, instead of showing IMG it's shows DSC. Could this have something to do with it? If so how can I fix it to where I'm able to print them & post them?

What the file name is has NOTHING to do with you not being able to print images from your files. I change the first three letters of my image files all the time so that I have an additional way of identifying them. I shot some of the meteor showers two nights ago so named my files AST. I name my personal image files with my initials

What is most important is that you make prints and post images from JPEG image files

My guess is that you are shooting in RAW and have not processed those images and exported them as high resolution JPEG images.

No, that doesn't have a thing to do with your printing issue. That's just the format Nikon's cameras use when naming files.

First thing I would check is what type of file your camera is saving. It almost sounds like you're shooting in RAW, which is a format that saves all of the data from the camera but needs to be processed before you can do anything with it. You can do that by opening the camera's memory card on your computer and either holding your mouse over an image icon until a popup appears or left-clicking on one of the files and looking at the details that appear at the bottom of the Windows Explorer window. If it says NEF file, you're shooting in RAW and you'll need to convert them to JPEG before you can upload to Facebook or have them printed. If you don't have a program that will do that, you can download a 30 day trial of Adobe Lightroom from the Adobe website.

To change the settings on your camera if you're only recording NEF files, hit the Menu button and go into the Shooting Menu. Select Image quality, then pick one of the options that saves as JPEG. That'll give you files you can upload straight to Facebook or Walmart.