A common cause of this error message is adding more ul elements to your page instead of adding a class.
You should only have two ul elements but maybe you added more and now you have four. When the instructions said to add a class to the first
<ul> element you instead created a whole new ul element.
This exercise is trying to get you to add a class:
class="pull-right" to each of your existing
<ul> elements, it isn't expecting you to add a new ul element.
There is no need to delete or replace your existing
<ul> elements, the exercise is asking you to add a class to your existing elements.
This is probably a good time to make sure you understand that there are elements, like p, ul, li, div and these elements have attributes, like class. Here are links to refresh your memory: ul is an element, class is an attribute.
You don't need to delete, replace or recreate an element in order to add an attribute to it, just add it!