In case that - after having perused the linked resource(s) - there's still some specific problems or questions remaining, I'd encourage you to just ask here.  The Monks will be happy to help anyone who's made a reasonable effort him- or herself. That's part of what this site is for.

Just (try to) clearly describe what you want to happen... for example by showing what you've tried — ideally, some self-contained snippet of code together with sample data, not forgetting to mention what the desired/expected result is, and what happened instead.

Thanks for all the suggestions, but I'm still hitting a road block. I don't want to post too much of my code as I am trying to really understand hashes instead of someone just fixing my code.
I think a better question for me now is, how can I pass variables into a hash. Here is a snipit of my code, the variables are defined outside of the while loop.

while <(inFile)> {
     my @record = split /\|/, $_;
     my %eslist = $record[3];
}
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Ultimately I want to output the unique entries in eslist but I can't even get it to count the number of keys in the hash and I'm getting a "odd number of elements in hash assignment" errors when using use warnings. I'm guessing there is something wrong with how I am trying to pass $record3 into the hash.
When defining the hash I've tried %eslist; and %eslist=(); but I still get the same errors.

A hash stores a key and a value so it doesn't make sense to assign an odd number of elements to a hash. Perhaps your code should look like:

my %eslist = ($record[3] => 1);
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---

True laziness is hard work

     my %eslist = $record[3];
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That code declares a hash variable (using my) and assigns a single scalar value to the hash. In the words of diagnostics

(W) You specified an odd number of elements to initialize a hash, 
which is odd, because hashes come in key/value pairs.
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What is in $record[3]? What other data do you want to associate with $record[3]? If you show us a small sample of data, we could probably suggest how you might store the data in a hash.

Give perldata a quick read.

OK, I think I see what you are trying to do, but a hash may not be what you want. A list might be better for your needs. List ex:

use List::MoreUtils qw(any);  #instead of using: 
                              #     "if (grep( m/whatever/, @list)){}"
                              #use: "if (any { m/whatever/} @list){}" 
                              #this exits on the first occurrence.

if (!any {m/^\Q$record[3]\E$} @esList){ 
   #the \Q\E guarantees that the value held in the $record[3] 
   #is not interpreted as a regular expression

    push (@esList = $record[3]);
}
### @esList is now a unique list of the values you want...
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But if you really want to use a hash, this is how you might do it:

my %esList = ();
$esList{$record[3]) = 1;

### then to recall all the found records:
foreach my $result {sort(keys(%esList))){
    print "found record: $result \n"; 
}
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Also, if you're interested, I started a discussion recently about how to best implement multidimensional hashes, they have some unique characterictics that you might not expect when trying to extending principals of a one dimensional hash. But there are some very good references listed there. It can be found at: Best Multidimensional Hash Practices? Good luck...

Maybe also the perldocs as well? I always find them useful and i like the FAQ style example code : this and this. Maybe also the camel book / cookbook (both o'reilly press) if you have them?

Knowing what you have in a complex data structure is often half the battle. How can I visualize my complex data structure? may help.

for ($i=0; $i < @keys; $i++) {
  if ($keys[$i] eq $key) {last}  # 'last' exits from the for loop
}
if ($i < @keys) {
  # $key already exists in the hash
  $values[$i] = $value;
} else {
  # $key is new
  push @keys, $key;
  push @values, $value;
}
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