BES: BlackBerry Enterprise Server
BWC: BlackBerry Web Client
When you started service on you BB they should have told you which one you were on. Most of the time, if you got your BB from work you're probably on a BES.
To SYNC, make back ups, load applications and to restore you need the Desktop Manager. You can go here:BIG FAQ! Software, Upgrade, Ringtones, Themes, Internet, IM, Modem, Tips+Tricks, Etc
and you will find a lot of info.
If you bought your BB new, you should have gotten a CD with it. Thats the Desktop Manager. Hope this gets you going.