a content item，应该就是一条具体的内容条目。所以已经默认是属于某个内容类型的item了。
创建举例
Content > Add content > Basic page (node/add/page). > Edit summary. > Preview > Save
修改举例
直接到Manage administrative menu, navigate to Content (admin/content)，选一个去修改内容即可。注意可以提供修改版本：
Check Create new revision under Published, if it is not already checked, and enter a Revision log message explaining what changes you are making (for example, you might enter "Updated opening hours"). This text will appear in the revision log for the page.
