It is easy to use the Zotero Connector browser plugin to automatically save references as you go along. But sometimes you will want or need to manually save references in Zotero:
The screenshots below show the desktop version of Zotero. The web version looks very similar and works almost identically, so there's no need to separately show it.
To manually save a journal article, for instance, click the "New item" button above the center column, then choose "Journal Article:"
Now, in the right pane, enter the details of this journal article:
The "New Item" menu shows a few common types of references. If you mouse over the "More" submenu, you get a list of almost all the types of items Zotero support:
The Desktop version of Zotero intentionally obscures the option to manually reference a webpage. This is because it is easier and more powerful to reference a web page using the Zotero Connector browser plugin. See the "Automatically enter references" tab for more details.
However, it is possible to manually add a reference for a webpage. First you will need to manually create a reference for some other type of item. Then, in the right pane, choose "Web page" from the "Item Type" drop down: