Ok, what do you do is set the parameter for
log_archive_dest_1 or log_archive_dest
in init.ora found in oracle_home\admin\sid\pfile
Log_archive_start should be true
log_archive_dest_1 or log_archive_dest, whichever version you are using. Here you should indicate the dir, in which you are going to store the archive files, mention the full path.
log_archive_format usually the format in which you want to store the archive files, something like arch%t%s.log. Here %t refers to the redo log thread number and %s refers to the log sequence number.
Shut down the database with immediate or normal option.
connect to sqlplus as internal
startup the database with MOUNT option
alter database archivelog
then open the database
this will enable archiving of the database permanently.