How to give leave approval rights ?

How to give leave approval rights ?

who is a leave approver,
The employee's immediate supervisor is responsible for review and approval of leave requests. The supervisor must verify whether the employee has the necessary paid leave available before approving a request for paid time off.

Following are steps To approve leave rights : 

1.  Go to Admin >> Select "Manage Security"
2.  Select the selective group to whom you want to give the rights 
3. Click on Rights >>  Select 'leave' > Select 'Approve or Reject leave' under the menu