Programmatically create an instance of a node using the Entity API/Entity Metadata Wrapper

entity_create.php

<?php
  //Load instance of entity
 $node = entity_create('node', array('type' => 'content_type'));
 $entity = entity_metadata_wrapper('node',$node);
 
 //Set properties
 $entity->author = $user->uid; // Author
 $entity->title->set("String");  //Title
 $entity->field_name->set("String"); //Textfield
 $entity->body->set(array('value' => "String or HTML")); //Body   
 
 //File field
 $entity->field_file[0] = array('fid' => $file->fid, 'display' => FALSE);
 $entity->field_file[0]->description = 'foo';
 $entity->field_file[0]->display = TRUE;
 $entity->field_file[1]->file = $file;
 
 //Images - assuming you have access to a $file object
 $entity->field_image = array('fid' => $file->fid);
 $entity->field_image->alt = 'foo';
 $entity->field_image->file = $file;
 $entity->field_image = array();
 
 //Save
 $entity->save(); //Save new instance
?>