Go to http://codex.wordpress.org/ WordPress_Lessons for lessons on how to update your wordpress site.
How to Copy over your files from your old homepage.
1. Login to your website.
2. Go to your Dashboard or click Site Admin from the menu.
3. On the left side, click Media, then click Add From Old Homepage.
4. You should see a list of all your old homepage files and pictures.
5. To add all of them, click the box beside File and it will select all the files.
6. Click the blue Import button at the bottom of the page. It might take a few minutes to import all your files. Please wait for it to finish or it will not copy.
7. Now you can insert your old pictures into you new site by clicking the Add Media button when you create a post or page.
8. Repeat this process if you have multiple folders with files in them.