Now that you know how to submit the 'data', you will need to retrieve it in your CGI script.

use strict;
use CGI;
my $query = new CGI;

## This will get the 'value'
my $selected_value = $query->param('color1');
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Update:
I just noticed that you are using 'multipule' in your select.
The onchange event will not allow you to select multipule items.
You will need a seperate 'submit' button for that to work.

If you need multipule 'values', use this to put the values into an array.

my @selected_value = $query->param('color1');
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