You'd use Javascript, or some other technology that embeds program instructions in HTML code. Perl can't, in general, be used *within* an HTML page without a special framework far more complex to set up than using CGI.pm. But assuming that what you seek is information on how you would write a script that would accept output from an HTML form and redirect the user's browser based on that output, you *should* use CGI.pm to gather that information, or failing that, CGI::Lite. Unless you have some very good reason for not wanting to use CGI.pm ?
perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>);
+$rose = "smells sweet to degree $n"; *other_name = *rose; print "$oth
+er_name\n"'
