If that really is a code snippet, it looks like you need to take a basic programming course. When you say

my $new_url = "http://www.google.com/search?q=$a" ; 
my $new_url = "http://hotbot.lycos.com/?MT=$a" ; 
my $new_url = "http://www.altavista.com/sites/search/web?q=$a&kl=XX&pg
+=q" ;
[download]

you are assigning three different values to the same place in memory, one after another, without doing anything to them.

If, as others have suggested, this is homework, you should seek help quick. Go immediately to your teacher and show them how far you have got. You may feel stupid doing this, but feeling stupid is part of learning.

On the other hand, if you have a better idea of what your doing than you post seems to suggest, you need to supply some error messages, and MORE CODE, so that the monks can help you further.

- Boldra