menubar, how to send data in fragment

WelcomeActivity.kt

package com.kantapp.wizito.v1.Activity

import android.support.design.widget.Snackbar
import android.support.v7.app.AppCompatActivity

import android.support.v4.app.Fragment
import android.support.v4.app.FragmentManager
import android.support.v4.app.FragmentPagerAdapter
import android.support.v4.view.ViewPager
import android.os.Bundle
import android.view.LayoutInflater
import android.view.Menu
import android.view.MenuItem
import android.view.View
import android.view.ViewGroup

import com.kantapp.wizito.R
import kotlinx.android.synthetic.main.activity_welcome.*
import kotlinx.android.synthetic.main.fragment_welcome.view.*

class WelcomeActivity : AppCompatActivity() {

    private var mSectionsPagerAdapter: SectionsPagerAdapter? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_welcome)

        setSupportActionBar(toolbar)
        mSectionsPagerAdapter = SectionsPagerAdapter(supportFragmentManager)
        container.adapter = mSectionsPagerAdapter

        fab.setOnClickListener { view ->
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show()
        }

    }


    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        menuInflater.inflate(R.menu.menu_welcome, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        val id = item.itemId

        if (id == R.id.action_settings) {
            return true
        }

        return super.onOptionsItemSelected(item)
    }
    inner class SectionsPagerAdapter(fm: FragmentManager) : FragmentPagerAdapter(fm) {

        override fun getItem(position: Int): Fragment {
            return PlaceholderFragment.newInstance(position + 1)
        }

        override fun getCount(): Int {
            // Show 3 total pages.
            return 3
        }
    }

    class PlaceholderFragment : Fragment() {

        override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                                  savedInstanceState: Bundle?): View? {
            val rootView = inflater.inflate(R.layout.fragment_welcome, container, false)
            rootView.section_label.text = getString(R.string.section_format, arguments?.getInt(ARG_SECTION_NUMBER))
            return rootView
        }

        companion object {
            /**
             * The fragment argument representing the section number for this
             * fragment.
             */
            private val ARG_SECTION_NUMBER = "section_number"

            /**
             * Returns a new instance of this fragment for the given section
             * number.
             */
            fun newInstance(sectionNumber: Int): PlaceholderFragment {
                val fragment = PlaceholderFragment()
                val args = Bundle()
                args.putInt(ARG_SECTION_NUMBER, sectionNumber)
                fragment.arguments = args
                return fragment
            }
        }
    }
}