....or use muslin. I hear that many quilters use muslin as our ancestors did.

What size is your quilt top? You can piece a back but I prefer to order a "wide back" or fabric that is 106-120 inches wide. Thousands of bolts is on line and they offer lots of different wide back fabrics. I don't like to use muslin because it isn't as high quality as regular fabric. I don't want to take a short cut after all that work and money spent on the top.

I have a group of friends who buy cotton sheets in the colour , fleece , charity shops or try online. I purchase large lengths 5yards of sale fabric . Not necessary the fabric for that quilt next one maybe. Also start to look at batting / wadding. This goes in between the top and back. Poly, cotton or mixtures look up a local shop. Come back or look up how to sandwich before you do it. It may be a good idea to make a cushion or a mat for a table to see how things work.
Don't forget come back here for any small thing somebody will have the knowledge to help.

I have ordered online a few times. I do not know about currency exchange, but if you worry about it, there may be some that deal with Euros. It is easy, and you have access to so many stores that you might never see in person.

Welcome to the world of quilting. You have come to the right board to ask your questions and learn tons of information. The ladies here are patient and willing to share their knowledge to us newbies.

I used a baby crib sheet on a quilt for backing and it worked great. I save sheets for this purpose. I've gotten sheets at estate sales (check for stains). All depends on the subject and situation. Actually, it just depends on your choice. Ask a local where you can get yardage.

you can order from thousandbolts.com: connectingthreads.com: marshalldrygoods.com or any number of great online sources since you have an APO box, shipping is the same cost as domestic mail. Your options are "backing" fabric which is generally 108" wide or regular fabric. Regular width yardage can be sewn in strips until it is the correct width. There are formula's available that will tell you how many yards to buy to piece for which size quilt. Or you can go to the PX and buy high cotton content flat sheets and use those.

Welcome! From one Army wife to another - Many, many thanks for your service! Your support means everything to your husband!

Armywife, you can get sheets at the PX that work really well. I think the reason the quilt police frowned on that in the past was because they used to be so tightly woven that they were difficult to hand quilt.
I had to resort to sheets when we were stationed in Gitmo and they worked fine. Now I buy bolts of 108" wide muslim at JoAnn's when I have a 50% coupon and always have it on hand. I never did see the point in putting all that work in the top just to have someone like the back more.

oops, riutzelj had the same idea while I was typing. Needless to say, I agree with her. LOL BTW, I'm a Navy Wife.

I don't know how new to quilting you are but when you sandwich the quilt top with the backing, be sure to leave at least 2" extra batting and backing around all sides of the top.

Go to ebay and get a cheater quilt the size you need. It's cheaper and you then have a reversible quilt.