How do I access items in my iCloud account?

According to my iPhone I have almost used up all of my 5 gb in my iCloud account. When I try to access my iCloud account on my mac I don't know where to find all the items saved in here? What am I not getting? Where should I be looking? All I see are the contacts, email, calendar tabs etc but it has nothing in it when I click. What happen to my photos I supposedly backed up? Keep in mind, I am new to this and this is my first time accessing my iCloud account.