Seeing as your using

$query->textfield(-name=>'Company_Name',-size=>20);
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you must be using the CGI module, so you need to use

$query->popup_menu(-name=>'Company_Name',-values=>\@first_entries);
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values will accept an anonymous array

['company1','company2']
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a pointer to an array as above

@first_entries=('company1','company2');
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and will be ordered as presented. However you can otherwise specify which element should be presented by default

-default=>'company1'
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finally you could (for example) want the script to call the companies by url while the dropdown box displays the company_name (or more likely to use id fields) in which case

@values=('URL1','URL2','URL3');
%labels=('URL1'=>'company1','URL2'=>'company2','URL3'=>'company3');
print $query->popup_menu(-name=>'Company_Name',
  -values=>\@values,-labels=>\%labels,-default=>'URL2');
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As for getting the data in there....there's more than one way to do it :-)