> So, what should I do, to find files that are modified within 3 days?
>

It's obscurely noted in the manual, but for numbers:

+n means greater than n
n  means exactly n
-n means less than

So you would want:

find path -mtime -3

Dan Mercer

find -mtime -5 -printf "%TY-%Tm-%Td %TT %p\n" | sort