Summary:
1-Find desired activity's complete name in Nook.
2-Set your intent classname with it.
3-Start your intent.
Details:
1-a:Connect your device to PC that you are developing your project.
1-b:Open Hierarchy view perspective
of eclipse and then open Windows
in that perspective.
1-c:Open your desired Activity manually in device.(home -> setting -> ...)
1-d:It may be need to do refresh on Windows
in perspective.
1-e:All existing Activities with their complete name and package name must be seen in Windows
in Hierarchy view perspective
.

For example,here my desired activity name is:com.android.settings.WirelessSettings
and it's package name is com.android.settings
.
I hope this snippet code help you to continue:
b1 = (Button) findViewById(R.id.button1);
b1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent();
i.setClassName("com.android.settings",
"com.android.settings.WirelessSettings");
startActivity(i);
}
});
For more details on Calling App from another
you can see this questions: Q1 - Q2