Oops, sorry for the previous message.

There's more to be said. The problem is in fact almost trivial and has a multitude of solutions. What you need is one more observation: find that sum of numbers on a single circle. (Just between us it's gong to be 39.) That sum when divided by 3 gives 13 which can be represented as the sum of numbers 1-12 in 6 different ways. So you have 6 pairs of numbers. And 6 pairs of circles. Each pair of circles intersect at exactly two points. Place pairs of numbers on pairs of such intersection points. Any way you do that will work.

Regards,
Alexander Bogomolny