I have 111 reputations and want to add 50 bounties for my this question: pfSense not forwarding DNS to concerned VPS
Please advise how can I add them
Please read https://serverfault.com/help/bounty
The important part for you:
A bounty can be started on a question two days after the question was asked.
This means you just can't add a bounty to your question less then an hour old yet.
In my opinion: Save your rep points and use them to participate in the site. Bounties are not worth the hassle.