Help, my 12th Hsc score is less, so i want to appear for the improvement examination , please can anyone give me more information about it .

12th score is 44.5% ,i wanted in addmissions in pune university ,as i belong to open category the total needed of the combination of subjects is 135 But my score 128 , i heard about the improvement examination please give me some more information of the same . i completed my 12th on march 2013. help