Demo content upload

I am looking for the home page templates, and presumably I have to upload the demo content. But when I tried to upload it before and used that “wordpress database reset” plugin you suggested, I deleted my entire database. I have a working, existing site, and a lot of these instructions seemed to be geared toward someone creating a new site from scratch. It would be helpful to have things clearly identified as “things that will erase your whole site – beware” or “it’s okay to run this without erasing your whole site.”

Anyway, I want to upload the demo content, but I just want to verify: can I do this and not overwrite, delete or otherwise damage my existing site?

Thanks.