the free version at download.com. Just search on syncback.
Most Sync softwares have somewhat the same functions. I just found that Syncback has much easier interface hence more user friendly. Basically, you can sync between computers, back up or sync your files from your computer with flash drives. I usually sync files with flash drive and use the flash drive to sync to my other laptops.
So basically, at first you just need to create a new profile. For example, you want to sync "my documents" to a flash drive on E: drive. So you pick the "Source" as "My Documents" and the "Destination" on E: drive. Then you name the profile such as USB-1 or something. Then you have more options like how you want to handle any conflicts / same file names. You may choose to always replace the older file or ask you the questions. You can also set the priorities. For example, if your USB drive is only for backup, then you may choose that the source always replace destination or delete files in destination if not found in source.
You can create as many profiles as you want to sync to different devices or different priorities.
Just play with it a few times and you'll understand. It's really simple.
PLEASE USE a temporary file while you're learning to use the software. I don't want you to accidently erase you files.