Let the Buyer Beware!
Do not, under any circumstances, start your search for a free WordPress theme by entering “Free WordPress Theme’ into any major or minor search engine…
“Here be dragons!“
Some might offer clean files and coding consistent with WordPress theme standards.
But as a beginner, you have no way of vetting the quality of the coding, so why take the risk?
Free themes often contain malware, or back-doors that can be used to hijack your site.
Crawling back from a hack is anything but free, so it is best to play safe, and chose your theme from the many offered through of the WordPress Theme Directory.