To make 48 circle-in-squares, I cut 96 squares of fabric and 96 circles (based on a coaster or a template of the right size of freezer paper.) That was the hardest part!
I followed the tutorial link above to a T and, given that I am NOT a perfectionist, came out with 48 pretty nice little circles inside squares. Sewing in a circle on the machine was helped by a tip from another site: stop with the needle down at every point on a clock or compass (whichever you prefer) to lift the foot and slightly turn your fabric. This makes for a smooth looking curve without bunches.
This was mostly just a matter of staying organized... and I really did not pay attention to which circles went on which squares, but let fate play a role!