As far as I know you have to have 30 activity points in order to reach Jr. Member rank on bitcointalk forum. And within the two 14 day period, you have to be active.
Good luck on your way to reach higher ranks. Have a blast mate
Besides of having a 30 activity points, you also need to have a 10 merit to be able to rank up. This is the new rule of the ranking system in bitcointalk. Merit can be given by other members of this forum who liked and commend your post as informative and useful. Goodluck ranking up!