Creating simple block module in drupal is easy you just need to concentrate on this artcile to learn to create simple block module in drupal step by step.
For drupal all block module whould uploaded to the folder sites/all/modules
Suppose I am creating an exampl module to display news from a single category.
Step 1: You Need to create one folder mydrupalnews and under that folder you need to crate 2 file mydrupalnews.info and mydrupalnews.module
Step 2: File mydrupalnews.info contain the information about the block
name = mydrupalnews
version = 1.0
description = “My Drupal News”
core = 6.x
PHP = 4.3
Step 4: file mydrupalnews.module contains the behavior of the block. In programming language I can say you need to code what ever you like here.
I am pasting the content of the file here for better understand of the coding.
$blocks[‘info’] = t(‘My Drupal News’);
$content = ob_get_clean();
$SQL = ‘Select * from category_node as cn
left join node as n on cn.nid = n.nid
left join image_attach as ia on cn.nid = ia.nid
left join image as i on ia.iid = i.nid
left join files as f on i.fid = f.fid
Where cn.cid =53 AND i.image_size = \’_original\’ order by n.nid desc LIMIT 0,3′;
// 53 is the category id of my site news. For your site you can change it easily.
$rowobj = db_query($SQL);
$content = ‘<div class=”news”>My Drupal News</div>’;
while($Row = db_fetch_array($rowobj))
$content .= ‘<div class=”box”><div class=”img_box”><div class=”img”><img src=”‘.$Row[‘filepath’].'” width=”92″ height=”92″></div>
<div class=”img_text”><a href=”node/’.$Row[‘nid’].'”><strong>’.$Row[‘title’].'</strong></a><br> <font color=”#996666″ style=”font-size:10px; padding-left:5px;” >’.date(‘Y-m-d’,$Row[‘created’]).'</font></div>
$blocks[‘subject’] = t(‘My Drupal News’);
$blocks[‘content’] = $content;
You are done with your programming. After everything done you just need to upload the folder mydrupalnews to the folder sites/all/modules
Now login to administrator go to module link publish your custom module. Now go to block link you will see your block is listed there in block page change the position where you want to display the block in your drupal page.