I recently found out that I need to update my operating system. I have already an External Hard Drive and have my pictures saved on there. plenty of room to do the time machine feature but My question and concern is.... if I press for the time machine to sync to my E Hard Drive, will that erase my pics?
Do not use the same drive for your backup. Get a different drive. It should have at least twice the storage space as your startup drive.
If you use the same drive and it becomes corrupted, then you lose everything. With separate drives you lose only one thing. If you want more security I suggest you make a separate backup of your photos and a separate backup of your backup.