<div id="form">

<form>

<script>
function checkValid(){
  var pass = document.getElementById("pass").value;
  var usrn = document.getElementById("usern").value;
  if (pass == "PSSSWORD HERE" && usrn == "USERNAME HERE"){
    window.open('You're in link here');
  }
  else{
    window.open('NOPE link here');;
  }
}

</script>



<label for="usr">Username:</label>
<input type = "username" id = "usern" name = "usr" style = "autocomplete:off">
<br>
<label for="psw">Password:</label>
<input type = "password" id = "pass" name = "psw">
<br>
<br>
<input type = "submit" value = "log in" onclick = "checkValid();">
<input type = "button" value = "back" onclick = "window.location.href = 'BACK BUTTON LINK HERE';">

</form>