To change the world "home": Find the file header.php and open it in a text editor (such as notepad etc.) and find the text "home" in a line about 4 lines up from the bottom. Change that to make it however you want it.
To change where it says "random images": Find the file sidebar.php and open it in any text editor. Find this line near the top:
Change the "random photos" text to whatever you want it to say.
To add more random photos: Find these lines just under the previous lines in your sidebar.php file:
<img src="<?php bloginfo('stylesheet_directory'); ?>/randomimages/rotate.php" alt="" width="48%" />
<img src="<?php bloginfo('stylesheet_directory'); ?>/randomimages/random.php" alt="" width="48%" />
Copy and paste so that you as many of these lines as you want photos, so right now there is two lines there, if you want 4 photos you would add two more lines. If you want the images to be the same size they are now, just add extra lines as is and I believe they will continue to line up in rows undernieth eachother, so 4 photos would be two lines of two photos each. If you want them in the same line you would set the width so that they will all equal a little less than 100% so for 4 images in 1 row, you would have 4 lines like: <img src="<?php bloginfo('stylesheet_directory'); ?>/randomimages/random.php" alt="" width="23%" />
Adding the extra images might take a little more code to make look just right so try this and let me know if you need more help.