1. Extract files from com_bfsurvey_basic_v1.2.zip

2. Copy entire contents (except css folder if you've customised style) of
"component" folder into /components/com_bfsurvey_basic/
(overwrite existing files).

3. Copy entire contents (except css folder if you've customised style) of
"admin" folder into /administrator/components/com_bfsurvey_basic/
(overwrite existing files)

4. Copy com_bfsurvey_basic.xml into /administrator/components/com_bfsurvey_basic/
(overwrite existing file)