jQuery 1.8.3 - How activate element from dynamic content?

jQuery 1.8.3 - How activate element from dynamic content?

Hi,
The problem can be found in many places - but no good solution. The dynamic reloaded contents can not be accessed from an pre-loaded scripts. Can someone make an example ?

This is my script:

HTML:
  1.    <select id="test">
  2.      <option value="2014">2014</option>
  3.      <option value="2015">2015</option>
  4.    </select>
  5. <div id="showme"></div>

SCRIPT:
  1. $("#test").on("change", function()
  2.     {
  3.     $.get("mysite.php?myvalue="  + $("#test").val(), function(data)
  4.         {
  5.         ;$("#showme").html(data);
  6.         });
  7.     });
  8. $('.field213').click(function()    { $(".feldfield213").html("itsworking");}
  9. $('.more').click(function()    { $(".more").html("itsworking");}

The result from "mysite.php" like this:

  1. <span class="field213" rel="12">test</span><span class="field2213" rel="144">test</span><span class="hi5" rel ="99">test</span>
  2. <span class="more">test</span>
(about 100 different span - classes)

How can i activate this classes after $.get?