How to start an Activity on MenuItem click?

You need to have to override onOptionsItemSelected method in your Activity, which is called when user clicks on the item in Options menu.

@Override
public boolean onOptionsItemSelected(MenuItem menuitem) {
    switch(menuitem.getItemId()) {
    case R.id.menu_item1:
        Intent intent1 = new Intent(this, ActivityForItemOne.class);
        this.startActivity(intent1);
        break;
    case R.id.menu_item2:
        // another startActivity, this is for menuitem with id "menu_item2"
        break;
    default:
        return super.onOptionsItemSelected(menuitem);
    }
    return true;
}