As a newbie, the bounty campaigns you can participate at are mostly social media and telegram campaigns. By heading on to this link - https://bitcointalk.org/index.php?board=238.0, you will find lots of bounty campaigns. What you need to do is just fill up forms and follow rules.
   Signature campaigns often give more profit than social media and telegram campaigns, but as a newbie it is hard to find a good project that allows newbies to join. To rank up to Jr. Member you need to have 30 activity and 30 posts. I suggest you try to answer some questions and share ideas in off topic too, it adds up to your number of posts. Once you have ranked up you can participate in most signature bounties.
   I hope this helped!