Cchan,
If you mean 'aligning text below the images' then I've been doing what daltonkost suggested, but this is such a basic requirement I decided to have a dig about for an 'easier' fix...
You need to edit: /includes/modules/YOUR TEMPLATE/category_row.php
If a folder for YOUR TEMPLATE doesn't exist in /includes/modules, then create one then copy /includes/modules/category_row.php into it.
eg. you're using the pure_black_free template, so create the folder /includes/modules/pure_black_free and copy category_row.php into it.
In category_row.php around line 39 you'll see...
$list_box_contents[$row][$col] = array('params' => 'class="categoryListBoxContents"' . ' ' . 'style="width:' . $col_width . '%;"',
'text' => '<a href="' . zen_href_link(FILENAME_DEFAULT, $cPath_new) . '">' . zen_image(DIR_WS_IMAGES . $categories->fields['categories_image'], $categories->fields['categories_name'], SUBCATEGORY_IMAGE_WIDTH, SUBCATEGORY_IMAGE_HEIGHT) . '<br />' . $categories->fields['categories_name'] . '</a>');
Now add an extra DIV tag named catImgWrapper around the image on that line (the two changed bits are in red)...
$list_box_contents[$row][$col] = array('params' => 'class="categoryListBoxContents"' . ' ' . 'style="width:' . $col_width . '%;"',
'text' => '<a href="' . zen_href_link(FILENAME_DEFAULT, $cPath_new) . '"><div class="catImgWrapper">' . zen_image(DIR_WS_IMAGES . $categories->fields['categories_image'], $categories->fields['categories_name'], SUBCATEGORY_IMAGE_WIDTH, SUBCATEGORY_IMAGE_HEIGHT) . '</div><br />' . $categories->fields['categories_name'] . '</a>');
The last thing you need to do is edit your stylesheet (in your case it is 'includes/templates/pure_black_free/css/stylesheet.css') and add...
.catImgWrapper {
height: 120px;
}
Obviously set the height to whatever you need.