How to use scripts to backup many folders

Best to create a script on Linux Client that will do everything in your list, then use crontab to kick off the script.
Add a User schedule in the policy with open window when user backups will be allowed.
No need for anything in Backup Selection or start_ or end_notify scripts.

1. Pre-backup script (Set DB with backup mode)
   (call script or add commands here)
2. backup of db configuration folder -
   /usr/openv/netbackup/bin/bpbackup <folder-name>
3. When first backup is finished a script must be executed (Stop data stream to index)
4. Wait 30 sec 
   sleep 30
5. Backup of data stream folder
   /usr/openv/netbackup/bin/bpbackup <folder-name>
6. When second backup is finished another script must be executed to end backup procedure (Start data stream and unset backup mode on DB)
   (call script or add commands here)

PS:
Any reason why you do not want to or cannot use NBU agents for this DB?

-f option needs a filename as argument.
This file will contain the list of folders/filenames to be backed up.

If folder list is specified as part of the command, it must be last in the command.

So, your command need to look like this:

/usr/openv/netbackup/bin/bpbackup -f /path/filename -p policy_name -s schedule_name 

or

/usr/openv/netbackup/bin/bpbackup  -p policy_name -s schedule_name /folder1 /folder2 /folder3  

See  NetBackup Commands Reference Guide  for command usage.