What Size Header Do I Use and How Do I Move the Sidebar

I am using the AdSmiple Theme and I would like to make 2 Modifications!
http://wordpress.org/extend/themes/adsimple

1. Instead of using the blog name as the header, I would like to use a picture header that spans across the page, also removing the search function.
How do I go about doing this? What size should the header be to fit?

2. I would like to move the middle sidebar to the left, so its the first sidebar. Any ideas how to do that?

Disclaimer: I know nothing about designing, CSS, CMS or anything else. But I am always open to learning.

 

Right,

Firstly, in the theme directory open the file : header.php - this is the file that controls the header - in some code editor (notepad will do)
remove the piece of code :

	<form method="get" id="search" action="<?php bloginfo('url'); ?>/">
			<input type="text" name="s" value="Search Keywords" onBlur="if(this.value=='') this.value='Search Keywords';" onFocus="if(this.value=='Search Keywords') this.value='';" id="s" />
			<input type="submit" value="Search" id="searchsubmit" />
		</form>

Code (markup):

This will get rid of the search form.

Next look for this code :

<h1 id="logo"><a href="<?php bloginfo('url'); ?>"><?php bloginfo('name'); ?></a> <span><?php bloginfo('description'); ?></span></h1>

Code (markup):

Replace that piece of code with the following :

<div id="logoimage"><img src="http://www.YOURDOMAIN.COM/(where the file is i.e images/logo.gif etc)"></h1>

Code (markup):

That will change the header BUT we then need to put in a piece of CSS code.

In style.css put the following at the bottom :

#logoimage {
   width: (WIDTH OF IMAGE)
   height: (HEIGHT OF IMAGE);
}

Code (markup):

Replacing the width and height.

Now to the sidebar, i'm afraid I can only speculate on this.
Maybe if you take this code out of sidebar.php :

      <div id="sidebar1">

<?php	if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('Sidebar 1') ) : ?>

				<div class="section">
					<h3>Categories</h3>
					<ul>
						<?php wp_list_categories('show_count=1&title_li='); ?>
					</ul>
				</div><!-- .section -->

				<div class="section">
					<h3>Tags</h3>
	      	<div id="tagCloud">
						<?php wp_tag_cloud('smallest=8&largest=18&number=100&orderby=name&order=ASC'); ?>
	      	</div>
				</div><!-- .section -->

				<div class="section">
					<h3>Meta</h3>
					<ul>
	          <?php wp_register(); ?>
						<li><?php wp_loginout(); ?></li>
						<?php wp_meta(); ?>
					</ul>
				</div><!-- .section -->

<?php endif; ?>

<?php if ( function_exists('pixel_sitemap')) pixel_sitemap($ps_count = 100); ?>

			</div><!-- end #l-sidebar -->

Code (markup):

And put that in the index.php above this piece of code :

<? get_sidebar(); ?>

Code (markup):

Then it might work, I'm stuck on that one though.