When one of your orders is filled, a small notification window appears on the bottom right hand of your screen. Fill notifications can be disabled, however, through the Trading Preferences menu , found at the top-right of the trading panel.
Cryptowatch can send you SMS text message alerts when one of your orders is filled. SMS alert settings can be configured through the Account menu, enabling you to change your phone number, as well as enable/disable the specific alerts you wish to receive.
You must have credits in your account to enable SMS text message alerts. Check Cryptowatch's Pricing page to learn more.