employee hierarchy using trace tree

Hi,
I am looking to create an employee hierarchy in a trace tree ( any other suggestions most welcome ) and have 2 specific fields in my table ( employee , reports to )


Now a sample data looks like follows
Employee     Reports to
User A           Manager A
Manager A     Senior manager A
User B           Senior Manager A
User C          Manager A


so on and so forth 


Now how do I get a trace tree so that when i click on Senior manager A  I get Manager A and User B , and then expand manager A to get user A and User C. 


I have been looking around a lot but cannot find a solution. 


Help appreciated. 
...