<span id="test">1</span>
<span id="test2">2</span>

<script>
  var s = document.getElementById("test");
  var s2 = document.getElementById("test2");
  //
  s.innerHTML="klfsdlkfj";
  s2.innerHTML="klfsdlkfj2";
  s2.style.color="red";
  s2.style.backgroundColor="yellow";
  s2.style.fontSize = "x-large";
</script>

<h1 id="imie"></h1>
<script>
  var s = document.getElementById("imie");
  var p = prompt("Podaj imię: ");
  if (p) s.innerHTML = p;
</script>