Bring the two ends together. The bricks will naturally curve into the circle shape. Join the two end pieces together.
Try experimenting with different patterns and sizes.
Want more 1x2 LEGO fun? Check out these other 1x2 bendy shape Instructables:
Lego Saw Blade
Lego Deltoid and Astroid
Lego Medical Sign
Be sure to follow so you don't miss out on other shapes!