What can be tested ?
- Fetching pages: type in a URL.
- Check if the HTML is correct.
- Check if elements of a page are in place.
- Follow links.
- Click on the link to the registration form,
- Fill in the fields (you'll have to play with this and fill in the fields with good values, bad values, find the edge cases etc.)
- White box: Check if the changes also took place in the backend. (e.g. in the database.)
- Check if you get back the correct response page.