You will normally find this sort of information on the Meta board. The thread you are looking for is the following: Enhanced newbie restrictions & requirements. In terms of ranking therefore, it affects you in terms of needing to obtain at least 1 Merit alongside >= 30 activity) to become a Jr. Member.

In addition, as you can see on the referenced link, you cannot have a signature nor a personal message until you do so (unless you decide to acquire a copper membership).