Select the track(s), right click, Send To, Web / FTP, Web or FTP Server...
I can't comment on whether or not it uploads summarily, or syncs. Synchronizing is more complicated, due to differences in file timestamps, time zones, size differences due to new line ending differences (in text files), and other things. I don't see such configurations in the dialog, so suspect is a simple if exists, don't transfer scheme, or blast away.
There are numerous FTP clients that provide excellent sync capability, in case MC doesn't meet your needs.