Can anyone suggest me how could i upgrade my Bitcointalk rank? 
Newbie needs 30 days to upgrade to junior member, although you need to post 1 or 2 post additional too that will increase your rank surely.
Yup. If you are a newbie you need 30 post so that you could rank up to jr. member. However you need to post additional one for you to rank up. It is a matter of patience because it really takes time. You also need to make you post good and clearly so that they can easily understand you point and they can give you a merit and it required to rank in member.