How to setup Wi-Fi syncing

[OSX 10.8.2, 1P 3.8.20 (build 31499), iOS iPhone version up-to-date and freshly reinstalled, everything's on the same wifi network, bojour seems to work fine, etc.]

Hi -- I was rolling along happily -- for years now -- only to realize iOS 1P hadn't synced in 5 weeks. So I futzed around, deleted the devices under sync in my OSX 1P sidebar, and now there's no 'sync' item at all. If there's any mention of syncing in the prefs, I can't find it; and most of the discussions and tutorials on the net seem to be out of date. --->>> What happened to the sidebar sync item, and how can I get it back? Sorry if this doesn't provide enough detail, but all the migrations went so well that I'm totally lost.