Once you have at least one field created, this screen becomes your main place to see and organize your fields. You'll see both fields you have created with CCK and fields added by other modules that CCK can't control. For instance, you'll see the content 'Title' and 'Body' on this screen. Each field has a weight that controls the order it appears when content is created or edited. If you have enabled the Fieldgroup module, you'll see your fields organized by groups. On this screen you can change the weight and group for each field. If you have no groups to select from, use the 'Add new group' to create them.

The weight controls the order that this field will appear in. Fields with heavier weights will appear after fields with lighter weights. Keep in mind that there are non-CCK fields in the content, too, and they have their own weights. For instance, the 'Title' field has a default weight of -5 that can't be controlled by CCK. If your content type has a body, the body has a weight of 0. If the content type uses taxonomy, the taxonomy has a weight of -3. So you need to select your field weights to fit in among other things in the content. If you have a lot of fields, it may be hard to fit them all in between other elements on the form. That's where fieldgroups come in handy, since you can put fields into groups, then organize them by weight within their group.

If you need to change the weight of a non-cck controlled form item, use hook_form_alter. For example, to adjust the Title weight from -5 to -10, create a form_weight.module and add this code:

<?php
function form_weight_form_alter($form_id, &$form) {
  if($form_id == "YOUR_FORM_ID") {
    $form['title']['#weight'] = -10;
  }
}
?>