How do I create new content type with editable fields?
Based upon the mentioned requirement, to me it seems either of the following situations:

For Drupal 7:


Theming the node add page: page--node--add--[content type].tpl.php
Theming the node edit page: page--node--edit--[content type].tpl.php


For Drupal 6:


Theming the node add page: page-node-add-[content type].tpl.php
Theming the node edit page: page-node-edit-[content type].tpl.php


More info about the same you can get from here:
https://drupal.org/node/1092122
https://drupal.org/node/1089656
https://api.drupal.org/api/drupal/modules%21system%21page.tpl.php/7