Calculate total time in oracle sql

Select Op.Operator_Name,Op.Emp_Code,

(Cast (Oplogin1.Signout_Time As Timestamp) - Cast (Oplogin1.Signin_Time As Timestamp)) As Licensed_Time,

(Cast (Oplogin2.Signout_Time As Timestamp) - Cast (Oplogin2.Signin_Time As Timestamp)) As Trainee_Time,

(Cast (Oplogin3.Signout_Time As Timestamp) - Cast (Oplogin3.Signin_Time As Timestamp)) As Superviser_Time

From Tblsapt_Operator Op

Left Join Tblsapt_Loginst_Operator1 Oplogin1 On (Op.Emp_Code = Oplogin1.Operator)

Left Join Tblsapt_Loginst_Operator2 Oplogin2 On (Op.Emp_Code = Oplogin2.Operator)

Left Join Tblsapt_Loginst_Operator3 Oplogin3 On (Op.Emp_Code = Oplogin3.Operator)

 

 

 

i am using the above query .using sql oracle i want to total "TRAINEE_TIME" with respect to EMP_CODE as mentioned in attached image. please help.