How to perform the 1-D signal filter?

Dear all,

Here I give a signal example and hope somone can show me how to
perferm the frequency filter on it.

;creat a signal data with two peaks in frequency domain at 2 and 3 Hz.
t=findgen(1000)/10.
data=sin(2*!pi*2*t)+sin(2*!pi*3*t)

freq=findgen(501)/100.
v=fft(data)
plot,freq,abs(v[0:500])^2,xtitle='frequency',ytitle='spectrum'


I want to filter the signal with the frequency higher than 2.5 Hz. How
do I do this?

I have read the help files about Digital_Filter and Convol, but I do
not know how to select the parameters for Signal_Filter.

Du