Pick a display name — we'll remember it:

Method — read the context before any payload
  1. Submit a unique marker (Udemy123) and look for where it goes.
  2. Devtools → search the marker: not a <p> this time — it landed inside <input value="Udemy123">. That's attribute context.
  3. Study how this value ends: a quote " then a bracket >.
  4. Adapt your payload to close it properly. Never plain copy/paste — the context decides.
Spoiler: two ways out of the attribute

Approach 1 — break out of the attribute and the tag, then own the page:

https://stuxnet.pro/xss/lab5/index.php?name="><script>alert(1)</script>

Approach 2 — stay inside the attribute and donate an event handler to the input itself (the lesson's second trick):

https://stuxnet.pro/xss/lab5/index.php?name=x" onmouseover="alert(1)

#1 fires on page load; #2 when you hover the field. Keep quotes balanced — and if the page prints anything after your injection into the tag, end with // so leftover characters become a JS comment instead of breaking your syntax.