I am trying to create a record using lightning-record-edit-form, however I am kind of stuck as to how to approach this. 
I want to include a toast message after the account creation, I understand that I have to create a handler in the lightning-input-field as well. But I am not sure how to do this. 

https://salesforce.stackexchange.com/questions/274178/lightning-web-components-save-form-data-to-the-controller

The above link shows what I need but it is kind of complicated for me. I am looking for may be a simpler code than this. 
Can anyone help me please?

Here is my code:
<template>
    <lightning-card title= "Lightning">
       <lightning-record-edit-form
       object-api-name={objectName}
       >
       <div class= "slds-box">
        <lightning-input-field field-name={fields.contactName}></lightning-input-field>
        <lightning-input-field field-name={fields.contactTitle}></lightning-input-field>
        <lightning-input-field field-name={fields.contactPhone}></lightning-input-field>
        <lightning-input-field field-name={fields.contactEmail}></lightning-input-field>
        <lightning-input-field field-name={fields.ccountId}></lightning-input-field>
        <lightning-button 
         class= "slds-m-around_xx-small" 
         variant= "neutral" 
         label= "Cancel" 
         onclick={cancelHandler}>
        </lightning-button>
        <lightning-button 
         class= "slds-m-around_xx-small" 
         variant= "brand" 
         label= "Submit" 
         onclick={saveHandler}>
        </lightning-button>
       </div>
       </lightning-record-edit-form>
    </lightning-card>
        </template>

JS:
import { LightningElement, api } from 'lwc';
import CONTACT_OBJECT from '@salesforce/schema/Contact'
import CONTACT_NAME from '@salesforce/schema/Contact.Name'
import CONTACT_TITLE from '@salesforce/schema/Contact.Title'
import CONTACT_PHONE from '@salesforce/schema/Contact.Phone'
import CONTACT_EMAIL from '@salesforce/schema/Contact.Email'
import CCOUNT_ID from '@salesforce/schema/Contact.AccountId'
export default class RecordEditForm extends LightningElement {
    objectName= CONTACT_OBJECT;
    fields= {
        contactName: CONTACT_NAME,
        contactTitle: CONTACT_TITLE,
        contactPhone: CONTACT_PHONE,
        contactEmail: CONTACT_EMAIL,
        ccountId: CCOUNT_ID
    }
    // cancelHandler(event){
    //     event.target.value
    // }
    // saveHandler(event){
    //     event.target.value
    // }
}.