Edit: Thanks to those who pointed out my mistake in which way up to lay the backing! Oops! I've now corrected that so it should hopefully make more sense now.
Hello! By now you should have your quilt top all sorted, with your circles fused and stitched down, so the next step is to make your quilt sandwich. Now, I will be the first to admit that this is probably my least favourite part of quilt making, but basting spray certainly helps makes it a lot easier, especially with little quilts like this. I use 505 Temporary Fabric Adhesive spray, which I purchased from Cottonpatch. (I think I have seen in in Hobbycraft too, but it might be more expensive there.)
Here's what I do:
Press your backing fabric and place it, wrong side facing up (if it has a wrong side that is), on a flat surface. Take your piece of batting outside, (or in a very well ventilated area - you don't want to breath any of this stuff in!) and spray one side. Then carefully lay the batting, sprayed side down, onto the backing fabric, smoothing it out as you go. The great thing about basting spray is that it is repositionable, so if you do find any wrinkles or puckers you can just lift it up and smooth it down again. Then, take the whole piece outside again and spray the top side of the batting. Place it on your surface and then carefully lay your quilt top on, again, smoothing it out as you go. Hopefully, it should look something like this:-
See how nice and smooth that is? Of course, you don't have to use basting spray. If you're not, I would probably recommend basting it with some large, widely spaced hand stitches, rather than pinning it, but it is entirely up to you, do whatever you're comfortable with.
Now we're ready to start quilting, but I haven't actually finished mine yet so I need to get on with that today so that I can come back with lots of pics for you tomorrow!