Place the file in a folder named wbfs/Donkey Kong Country Returns [SF8E01]/SF8E01.wbfs .
If your file is a .wbf1 (split file because FAT32 can’t handle files over 4GB), don’t panic. Donkey Kong Country Returns is under 4GB, so it should be a single .wbfs file. Donkey Kong Country Returns Wii NTSC-WBFS