Your apache server is trying to execute a perl script that is supposed to exist at this path on the host file system:

/var/www/cgi-bin/form.pl
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You should be able to do a shell login on the host, and see if that file exists in that directory. If you find that it's not there, you need to place a copy of your perl script there. If it is there, it might be having trouble because of unsuitable permission settings on the file (or on the cgi-bin directory, though this seems unlikely).

UPDATE: (forgot to mention) I've never seen/used CentOS, but if it's anything like unix/linux, then your script has some problems:

#!/user/bin/perl
require("cgi-lib.pl");
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The first line should be #!/usr/bin/perl (no "e" in "usr"). Also, the "cgi-bin.pl" file must either be in that same /var/www/cgi-bin directory, or else in one of the directories that your /usr/bin/perl has in its defauilt value for @INC.

Also, you have your last two close tags in the wrong order: </body> should be above </html>.