Installing purchased theme – 2 ways? Confused

Hello: I finally installed wp on my godaddy hosted acct at https://www.ramonasrefashions.com. When I go to dashboard -> appearance -> themes -> install themes it says “Install a theme in .zip format. If you have a theme in a .zip format, you may install it by uploading it here.” When i dowloaded the purchased theme it unzipped itself so i selected all the files together and right clicked compress and it created a file called archive.zip. But, when i try to install archive.zip it won’t let me and i get a failure notice. I checked my purchased themes directions on how to install and it says to upload the files using FTP like Filezilla but i’m very hesistant to do this because i have no idea what i’m doing and last time i did it wrong and was locked out for two days and had to reinstall and lost my work. Suggestions? Thanks