Once you have downloaded the Zotero software, it's a good idea to create a Zotero account so you can save and sync your citations online, as well as on your own computer.
To create an account:
Go to the Zotero website and click "Log In" in the upper right corner.
Then, choose Register for a free account.
After you have registered, open the Zotero software on your computer and click on Edit--Preferences--Sync
Enter the username and password that you just registered in the Zotero website and click the "Set Up Syncing" button.
You can export references from Scholar OneSearch from the search results page by clicking on the three dots on the right side of an item:
From the list of menu options, choose RIS (EndNote, etc.).
Once the RIS file has been downloaded to your computer, open Zotero and click File--Import and select the RIS file.