is a great resource for all things Blogspot. They guy who owns this blog actually converts WordPress templates for use with Blogger. Use the categories on the right to navigate the site. He has everything from template galleries to Blogger tweaks.
To change your layout in Blogger to a different Blogger template, click on Layout
from your dashboard. Click Pick New Template
to select from the choices Blogger has available.
To change your layout in Blogger using a template from Jackbook.com above, go to the page for one of the templates. For example:http://www.jackbook.com/blogger-templates-gallery/blogger-templates-creation
Scroll down until your see the links beneath the screenshot for viewing the demo, and downloading the theme.
Click to download the Blogger template and then follow the instructions from the page. The steps are always outlined really well, and you'll be up and running with a new template in no time. Best of luck to you!