Most likely you will have to post that you offer your service as bounty manager in the service section of this forum. As their name states they manage bounty campaigns. So they are the ones who check that other users completed the task correctly and that they fulfilled all the requirements. Bounties are simply a way for ICOs to try to create a buzz about them by offering you their tokens.

So you will have to have some knowledge regarding google docs, how to create sheets and google forms to enable users to apply and see where they stand. For some parts of the campaign you can even write some small bot a script that will do the job and thus simply fill the sheets if you want to cut down the work you have to do. But let's say signature campaigns for instance require you to skim through posts and ensure that your participants are not spamming etc.

Best would be to go to bounty section and try to see how other managers and doing their job.