My Japanese friend has just had a baby boy, how should I properly congratulate her?

Question:

My Japanese friend has just had a baby boy. I will bring her onigiri from my country when I visit next week, but are there other Japanese customs in this instance I should follow?

Thank you!

Answer:

Usually, Japanese people give money (10,000 yen or so in general) in this kind of envelop.
http://letter123.livedoor.biz/archives/5…

This is Japanese custom. But since you are not Japanese, there is nothing like you "should" follow this custom.