How to Send a post HTTP request to Back office

I’m using a Vue form to send data to a link and retrieve it from back.
The Problem is that the request fails to send data , showing POST http://localhost:8080/ 404 (Not Found), and i’m trying to properly send the data, using fetch or axios.

Here’s my Vue form with the script

<template>
  
<div class="ui left aligtned container">
</div>
<h1 class="ui teal header" >Gestion d'utilisateurs</h1>
<div class="ui relaxed divided list">
  <form class="ui form" @submit.prevent="SubmitForm">
      <h4 class="ui dividing header">User modificaiton</h4>
  <div class="field">
    <div class="two fields" v-for="user in users" :key="user.id">
      <div class="field">
            <label align="left" >Nom</label>
        <!-- <input type="text" name="nom" placeholder="Nom" v-bind:value="user.name" > -->
        <input type="text" name="nom" placeholder="Nom" v-model="form.nom" >
      </div>
      <div class="field" v-for="user in users" :key="user.id">
            <label align="left">Prénom</label>
        <!-- <input type="text" name="Prenom" placeholder="Prénom" v-bind:value="user.lastname"> -->
        <input type="text" name="Prenom" placeholder="Prénom" v-model="form.prenom">
      </div>
    </div>
    <div class="field" v-for="user in users" :key="user.id">
    <label align="left">Hiérarchie</label>
    <div class="fields">
      <div class="four wide field">
        <!-- <input type="text" name="hierarchie" placeholder="Hiérarchie" v-model="user.role"> -->
        <input type="number" name="hierarchie" placeholder="Hiérarchie" v-model="form.role" ref="hInput">

          <button >Update </button>
          <a class="ui button">Cancel</a>
  </form>
      </div>
  </div>
</template>

<script>
import axios from 'axios'

export default {
  data() {
    return {
      users:[],
      form: {
          nom: '',
          prenom: '',
          role: '',
            }   
    };
  },

  methods:{
    SubmitForm(){
      
      console.log('Nom: ' + this.form.nom);
      console.log('Prénom: ' + this.form.prenom);
      console.log('Hiérarchie: ' + this.form.role);

      axios.post('/', this.form).then(
      console.log('2'));
                 
    } ,
    
  },
  mounted()
    {   
        axios.get('http://localhost:8081/api/v1/users/6')
        .then(response => {(console.log(response.data))
        this.users=response.data;
        return response.name
        });
    },
};
</script>

as shown here i declare a form that contains values I want to send, then I send this form on the HTTP request