How do i programatically launch another application from my application

You can programatically launch another application from within your application using the SysUIAppSwitch function by passing it the sysAppLaunchCmdNormalLaunch launch code and a NULL parameter block.
Here is a code example that shows how to launch the built-in MemoPad application:

static void MainGotoApplication()

{

LocalID theDBID;

UInt theCardNo;

DmSearchStateType theSearchState;

// Grab the id of the application we want to launch (the memo pad)

DmGetNextDatabaseByTypeCreator(true, &theSearchState, sysFileTApplication, sysFileCMemo, true, &theCardNo, &theDBID);

// Launch the new app.

SysUIAppSwitch(theCardNo, theDBID, sysAppLaunchCmdNormalLaunch, NULL);

}