Question

your friend got first prize on debate competition, write an email congratulating him

Answer 1

congratulations my dear friend for your winning first prize in debate

Answer 2

Emails are the short version of a letter.

In it, you need to mention how happy you are for his win and ask him about his experience that you wanted to know about.

It can be the enthusiasm you have for your friend.

Then wrap it up on how you so want to meet him in person to enjoy this victory.