I would like to know following details below.
1. transaction logs will be deleted after successfull backup?
2. Configured backup for SAP Sybase full backup. Backup successfully completed.
3. I want to configure incremental backup. Incremental is a transaction logs backup?
4. How Do I include transaction logs backup backup script?
It's been awhile, but are you using the SAP BR*Tools to drive the backups from the client? NetBackup only acts as the pipeline from the application/data to the storage (tape or disk). I've never worked with Sybase, but this is how it worked for Oracle. The brarchive has several options that will control how the transaction logs are controlled.
Normally for a DB, and you should consider SAP nothing more then a DB, the incrementals would be just the archive logs. You can configure the full and archives in any combination you need to meet your companies requirments.
As for the scripts, I don't remember off the top of my head if I had to run a brarchive in conjunction with the brbackup, or if the brbackup did it for me. Here are some sample scripts for UNIX and windows. The full backup needs to get the current transaction logs or it's not complete.
The SAP help portal should also be able to give you some answers.