DB<114> @a=(12,-85,36,-10,75,-38)
 => (12, -85, 36, -10, 75, -38)

  DB<115> @a = grep { $_ >= 0 } @a
 => (12, 36, 75)
[download]

But for the basics people here appreciate if you first read docs (or a Perl book) and try the examples there before asking.

People already provided links (like here) and they would like to get feedback if those links helped (and if not, why, to be able to improve them)

Thats the way we help to learn efficiently! :-)