Capture an entire Webpage
These options are available with the browser extension added to your browser.
If Zotero recognizes the page, the "Webpage Icon" will be available in the browser bar. Zotero will save the content of the page and the metadata (Title, URL, date accessed, etc.) into your library.
Zotero can be forced to save the webpage as a screenshot by right-clicking (click-and-hold in safari) the save button. Choose the option: Save to Zotero (Web Page with/without Snapshot).
In both cases you will want to ensure that all the metadata is correct and complete. In the past, Zotero had a hard time with creator/author.