Changing Twenty Ten 1.1 header.php file into iBlog 3.0.6's header.php

start by editing header.php of TwentyTen, and remove all of this:

<?php
					// Check if this is a post or page, if it has a thumbnail, and if it's a big one
					if ( is_singular() &&
							has_post_thumbnail( $post->ID ) &&
							( /* $src, $width, $height */ $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'post-thumbnail' ) ) &&
							$image[1] >= HEADER_IMAGE_WIDTH ) :
						// Houston, we have a new header image!
						echo get_the_post_thumbnail( $post->ID, 'post-thumbnail' );
					else : ?>
						<img src="<?php header_image(); ?>" width="<?php echo HEADER_IMAGE_WIDTH; ?>" height="<?php echo HEADER_IMAGE_HEIGHT; ?>" alt="" />
					<?php endif; ?>

that will get rid of the header image; then borrow a few background images for the menu from iBlog; probably even get the code and graphic for the rss symbol, and the search form … done.

however, this is pure css cosmetic, and has not much to do with wordpress.

and – why not use iBlog in the first place?

yes, it is possible.
how easy it is and how long it will take, depends on your knowledge of css and html (although a lot of it will probably get done by copy/paste)

as you already managed to get your logo onto iBog, you probably know quite a bit of programming; and you should be able to do this again for TwentyTen.