I dont know if this is the right place, im new,
When i download and theme pack and upload the html folder to
my website through ftp. Where do i get the admin.php, config.php, and mainfile.php from . ?

Sorry if this is the wrong place and sorry if i am a noob lol

You need to download, upload and install a version of Nuke before you can upload themes:

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Once you've done that you upload your chosen theme to the themes folder and then choose it in your account.. job done.