Kies is very flaky, and fussy about sequencing of operations.
You should be able to download it from the Samsung support site.
Not sure you'll find it listed on your device. It's part of the system software and fires up when required.
Synch will be automatic, once you can establish a connection, which may take a few attempts. It also takes some time so be patient!
My experience is with the S1 and the Note, not the S3