create.php

<!-- Modal Structure -->
<form id="create-modal" class="modal" action="create.php" method="post">
  <div class="modal-content">
    <h4 class="row">Create a new user</h4>
    <div class="row">
      <div class="col s12">
        <div class="row">
          <div class="input-field col s12 valign-wrapper">
            <i class="material-icons prefix valign">account_circle</i>
            <input id="username" name="username" type="text" class="validate">
            <label for="username">Username</label>
          </div>
          <div class="input-field col s12 valign-wrapper">
            <i class="material-icons prefix valign">lock</i>
            <input id="password" name="password" type="password" class="validate" />
            <label for="password">Password</label>
          </div>
          <div class="input-field col s12">
            <h6> Access level: </h6>
            <input class="with-gap" name="access" type="radio" id="access1" value="admin" checked="checked" />
            <label for="access1">Admin</label> <br />
            <input class="with-gap" name="access" type="radio" id="access2" value="user" />
            <label for="access2">User</label>
          </div>
        </div>
      </div>
    </div>
  </div>
  <div class="modal-footer input-field">
    <button
      class="waves-effect waves-green btn-flat"
      type="submit" name="action"
      onclick="Materialize.toast('User created', 4000)"
    >
        Create
    </button>
  </div>
</form>