<form method="POST" action="index.php">
          <div class="form-group">
            <label for="exampleInputNume">Numele tău</label>
            <input type="text" name="Nume" class="form-control">
          </div>

          <div class="form-group">
            <label for="exampleInputEmail1">Email-ul tău:</label>
            <input type="text" name="Email" class="form-control">
          </div>

          <div class="form-group">
            <label for="exampleInputEmail1">Subiect:</label>
            <input type="text" name="Subiect" class="form-control">
          </div>

          <div class="form-group">
            <label for="exampleInputEmail1">Mesaj:</label>
            <textarea name="Mesaj"></textarea>
          </div>
          <div class="clearfix"><br/></div>
          <center><button type="submit" name="Trimite" class="btn btn-default">Trimite</button></center>
        </form>

        <?php

            $Nume = $_POST['Nume'];
            $Email = $_POST['Email'];
            $Subiect = $_POST['Subiect'];
            $Mesaj = $_POST['Mesaj'];

            mail('metin2dev.ro@gmail.com', $Subiect, $Mesaj);

        ?>