#
#-----[ REMOVE ]-----
#
PHPBB3_ROOT/portal/block/calendar.php
PHPBB3_ROOT/styles/prosilver/template/portal/block/calendar_2.html
PHPBB3_ROOT/styles/subsilver2/template/portal/block/calendar_2.html

#
#-----[ UPLOAD ]-----
#
CPOY root/portal/block/calendar.php TO PHPBB3_ROOT/portal/block/calendar.php
CPOY root/styles/prosilver/template/portal/block/calendar.html TO PHPBB3_ROOT/styles/prosilver/template/portal/block/calendar.html
CPOY root/styles/prosilver/theme/images/portal/portal_calendar.gif TO PHPBB3_ROOT/styles/prosilver/theme/images/portal/portal_calendar.gif
CPOY root/styles/subsilver2/template/portal/block/calendar.html TO PHPBB3_ROOT/styles/subsilver2/template/portal/block/calendar.html
CPOY root/styles/subsilver2/theme/images/portal/portal_calendar.gif TO PHPBB3_ROOT/styles/subsilver2/theme/images/portal/portal_calendar.gif

#
#-----[ OPEN ]-----
#
portal.php

#
#-----[ FIND ]-----
#

P.S.
Purge the cache.