copy the files > paste into the correct folder > click "replace the files in the destination"
overwrite means "replace the old files with the new ones, keeping the same file name"
which folder is the correct folder?
paste the files from the "[Eng] Balvenie's Birthday Party.zip" file into this folder: 발베니의 생일파티 [or whatever you named it]\www\data ; like the above tutorial said