jetpack compose - How to use Column layout

MainActivity.kt

package com.cfsuman.jetpackcompose

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.*
import androidx.compose.material.Button
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.text.font.FontFamily
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            MainContent()
        }
    }


    @Composable
    fun MainContent(){
        Column(
            Modifier
                .padding(16.dp)
                .fillMaxWidth(),
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            Button(onClick = {
                Toast.makeText(
                    this@MainActivity,
                    "Clicked",
                    Toast.LENGTH_SHORT
                ).show()
            }) {
                Text(text = "Click Me" )
            }
            
            Spacer(modifier = Modifier.requiredHeight(25.dp))

            Text(
                text = "This is a Text",
                fontWeight = FontWeight.Bold,
                fontSize = 25.sp,
                fontFamily = FontFamily.Serif
            )

            Text(
                text = "This is second Text",
                fontWeight = FontWeight.Bold,
                fontSize = 25.sp,
                fontFamily = FontFamily.Monospace,
                color = Color.Red
            )

            Text(
                text = "This is third Text",
                fontWeight = FontWeight.Bold,
                fontSize = 35.sp,
                fontFamily = FontFamily.Cursive,
                color = Color(0xFF0047AB)

            )
        }
    }


    @Preview
    @Composable
    fun ComposablePreview(){
        //MainContent()
    }
}