Backup TemplateThe first rule about changing templates is FIRST backup your current template. This is very easy to do in the New Blogger. Click the TEMPLATE > EDIT HTML tabs then click the "Download Full Template" link as shown in the screenshot below:
Save it in a suitable folder and use a filename like DummiesGuideToGoogleBlogger21jan07. So if anything happens, you can always go back to your previous template by first selecting the template you have downloaded by clicking the "Choose" button below the "Download Full Template" link, then clicking "Upload".
Changing TemplateTo change to a standard New Blogger template, click the TEMPLATE > PICK NEW TEMPLATE tabs, select a template you like by ticking the radio button against your choice. If you wish, you can preview it first (note that you can only do this if you have at least one post published). If satisfied, click "Save Template" (see screenshot below):
(TO BE CONTINUES)