You should do this, you break your HTML page into one script and your graph into another script. Within your HTML page you call the graph script passing it parameters that it will need to draw the graph. 
<!-- Your HTML page -->
<html>
<body>
<h1>My Graph</h1>
<p><img src="graphic.pl?width=100&height=100">
</body>
</html>

[download]
Now your script that will return the graph, 
use CGI;

my $q = CGI->new();

my $height = $q->param('height');
my $width  = $q->param('width');

#
# Include you GD stuff here...
#

[download]

I realize that this is not complete but neither is the code that you gave us to work with... :)

In reply to Re: Creating a Histogram by Herkum
in thread Creating a Histogram by arguelje

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.