You can't join signature campaign because of your rank. You need to rank up first to Jr member before you will become qualify for signature bounty. But don't be sad you can still participate in different social media campaign like twitter,facebook,telegram,etc...even you are just a Newbie. But while joining the campaign please so more reading here in forum to get more knowledge and information. You can find bounty campaign in bounty section...https://bitcointalk.org/index.php?board=238.0