rsync <options> /from/folder/path user@host:/path/to
Note about paths: /from/folder/path means send the whole folder, where as /from/folder/path/ means send just the contents of the folder.
If you want to send ~/sync so it ends up into ~/sync on the other computer then use: rsync -a ~/sync user@host:
The syntax is like that of
-a does recursive (so no need for r)
-P Shows progress and allows you to resume interrupted transfers.
--checksum verify checksum (currently MD5) when the time and filesize matches
-v for verbose
-n for dry run
-z compresses the transfers