You're not asking the right questions.

How does one, say, in a guest book limit the number of entries per page and number the pages, and at the same time alternate the back ground color between entries?

That is really asking "How do I do XYZ at a given point in a list of stuff?"

what is the syntax for eliminating a string from form input-namely "http://www." in a input type="text"name="url" situation.

That is really asking "How do I remove a substring from another string?"

You're too focused on your actual task to be able to learn the general principles. Take a step back and build slowly. Take some baby steps. Maybe, instead of working with the web, work in ASCII. Try running the following program:

use strict;

my @array = 1 .. 10;
my $num_per_row = 4;

foreach my $i (0 .. $#array)
{
    print $array[$i], ' ';
    print "\n" unless ($i + 1) % $num_per_row;
}
print "\n";
[download]

Use the principles in that program to do that image gallery thing.

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.