Hi Niwantha, If you choose sentence 1, you need the use of appositives to separate the name from the rest of the sentence so that it is clearer: Thanks, Johan, for sharing. If you choose sentence 2, you need a comma to separate the name from the rest the sentence again, as you are using the vocative case to emphasise on the person being spoken to: Thanks for sharing, Johan. Just as a side discussion, if a comma is not used, an unsuspecting reader may have the impression that Johan is being shared by a few people. Hope this helps. Cheers

I think the second is slightly more natural but use of either would be perfectly acceptable.

BTW Where to place .... is not a question. How to .. also Where should the name be placed ....? Where would I put the name .....? Tell me where to place .... <-- not a question.

Choose from John. thanks for sharing and Thanks for sharing, John.

In my opinion, the second is more natural. That's how I would say it.