Yes, to add any theme to WordPress, you just copy the Theme folder into wp-contents/themes and then go to the dashboard->appearences->themes and select the thems ou want to activate.
when you move the new version of atahualpa in, name the folder with the version (i.e atahualpa333, atahualpa342 etc) so you can identify them easily if you want to swap.
Also remember, you need to copy any images you placed in ..images/header/ into the ..images/header/ of the new theme folder
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Juggledad | Forum Moderator/Support