You must pry (carefully) the top off, you only have half of it off right now....the O rings are under. Take notice to the orientation as it is asymmetrical. I just did this job on my car and my O rings looked fine, but after replacing my O rings with new ones it stopped leaking. Make sure you get the exact O rings and don't just come close with these.
look at this diagram, you can see the two different size O rings under the part you still have in;
Dwight