I'm helping with our organization's website here on Bravenet (Society of Washington Artists), but my experiences is with iWeb and EverWeb on the Mac platform. This is a bit "Greek" to me, but I see some templates that seem very workable for our needs. My question: Can I use these templates to teach myself and prepare for teaching others on our team and prepare for changes in the future? That is to say, create "practice sites" without taking them live, but keeping them in our account files?
As Peter said, if you are using the Site Builder you can indeed do that, although you will want to be careful about where and what changes individuals make as having access to the Bravenet account grants access to all files and services associated with the account; which can easily lead to somebody accidentally overwriting your main site, or something equally problematic.
If you are using the Web Hosting service, you'll have no problem creating subdomains to practice on.
You could have a secondary Bravenet account, intended solely for practice, assuming the service you wish to use is the Site Builder (there is no access to Web Hosting from free accounts). This would prevent any changes from practice content carrying over to live content.