How to do incremental backup?

A differential backup backs up only the files that changed since the last full back(you do know what full backup is, right?). If you lose one of the differential backup files you can still recover other files.

Incremental backups back up only the changed data, but they only back up the data that has changed since the last backup — be it a full or incremental backup. So if you lose one incremental backup file you cannot recover the following files.

Incremental backup saves more time and space, while differential backup is more safe.

For incremental backup software, according to Google, the first one is acronis($49.99) and the second one is free todo backup

http://www.acronis.com/en-sg/resource/solutions/backup/2005/incremental-backups.html
http://www.todo-backup.com/products/features/incremental-backup.htm

Incremental backup refers to back up the changed and new added data based on the first full backup or the last backup.differential backup is used to back up the changed data based on the last full backup.in order to do incremental/differential backup,you can try free AOMEI Backuper
the more differences and guide please see the article below
http://www.backup-utility.com/features/incremental-differential-backup.html