WordPress MU

I have customised theme on my site http://supari.org.

i want to add functions of plugins on post
(eg: last 10 post headers of a perticular category)

i am not expert in PHP or scripts but i can add modify scripts

is there any inbuilt functions which can be called by <php include...> or small scripts to things.
let me know.

There's a plugin called Custom Function Widgets that might be useful. It allows you to insert custom PHP functions in the sidebar (NOTE: I don't believe it allows you to insert code directly into posts).

thank you for the reply;
im not asking for widgets;
i have one like below; but if i select more than one post header; its comes in one line;
is there php expert to make it like comes each post header in next line.

thank you in advance.

<div id="home_artic"> <!-- start home_artic -->
<h3 class="home_artic"><B>Articles</b></h3>

<?php $the_query = new WP_Query('category_name=articles&showposts=7');

while ($the_query->have_posts()) : $the_query->the_post();

$do_not_duplicate = $post->ID; ?>

<div class="humo_content">

<?php if ( get_post_meta($post->ID, 'humor_home_img', true) ) { ?>

<div class="humo_thumb">" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><img src="<?php bloginfo('stylesheet_directory'); ?>/images/artic/<?php echo get_post_meta($post->ID, "humor_home_img", $single = true); ?>" alt="<?php the_title(); ?>" /></div>

<?php } ?>

<div class="humo_title">" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></div>
</div>

this is just to add plugin / widget functions to theme, without plugin / widget
so i can design blog as i like.