To launch application you have to know ID. There is example in documentation:
tizen.application.launch(ApplicationId id, optional SuccessCallback? successCallback, optional ErrorCallback? errorCallback);
or:
tizen.application.launchAppControl(
appControl,
appId,
function() {console.log("launch application control succeed"); },
function(e) {console.log("launch application control failed. reason: " + e.message); },
appControlReplyCallback );
You can find information in Tizen SDK help:
API References > Device API Reference > Application
and
Programming Guide > Device API Guides > Application Guides
You need the permission: http://tizen.org/privilege/application.launch