Rolling Total And Sorting Record

Dear All

I have the following table structure and following data

create table emp
(
empid char(4),
empname char(10),
empsal money,
empsalPercent money,
empsalRuningTot money
)

empid empname empsal empsalpercent
e001   tom          20.00     8.69
e002   ***         40.00     17.39
e003   harry        15.00     6.52
e004   masum     25.00    10.86
e005   rana         30.00     13.04
e006   dipak        60.00     26.08
e007   rana         40.00     17.39

now would like to make the following

1) want to sort first emp table based on empsalPercent field on descending order physically
Prob : am only able to select the same thru descending order but am unable to make it physical shorting
select * from emp order by empsalPercent desc

2) after make descending order for empsalpercent I want to make RunningTotal for the EmpsalPercent column

pls help
samir